OWASP Top 10 for API Security: A Complete Guide
APIs are critical for modern software, but they also introduce unique security risks. 91% of organizations reported API security incidents in 2020, and attacks have only grown more frequent and severe. The OWASP API Security Top 10 is a framework designed to tackle these vulnerabilities, helping organizations secure APIs against threats like Broken Object Level Authorization (BOLA), Excessive Data Exposure, and Server-Side Request Forgery (SSRF).
Key Takeaways:
APIs now account for 83% of web traffic, making them prime attack targets.
The average cost of an API breach is $4.88 million, as seen in the 2023 T-Mobile breach impacting 37 million users.
OWASP’s framework highlights the top API risks, such as Broken Authentication, Security Misconfiguration, and Rate Limiting Failures.
To secure APIs:
Use strong authentication (OAuth 2.0, MFA) and authorization (RBAC).
Validate inputs, enforce server-side filtering, and limit data exposure.
Apply rate limiting and monitor traffic for anomalies.
Regularly test APIs against OWASP standards using tools like Qodex to automate vulnerability detection.
APIs are critical for modern software, but they also introduce unique security risks. 91% of organizations reported API security incidents in 2020, and attacks have only grown more frequent and severe. The OWASP API Security Top 10 is a framework designed to tackle these vulnerabilities, helping organizations secure APIs against threats like Broken Object Level Authorization (BOLA), Excessive Data Exposure, and Server-Side Request Forgery (SSRF).
Key Takeaways:
APIs now account for 83% of web traffic, making them prime attack targets.
The average cost of an API breach is $4.88 million, as seen in the 2023 T-Mobile breach impacting 37 million users.
OWASP’s framework highlights the top API risks, such as Broken Authentication, Security Misconfiguration, and Rate Limiting Failures.
To secure APIs:
Use strong authentication (OAuth 2.0, MFA) and authorization (RBAC).
Validate inputs, enforce server-side filtering, and limit data exposure.
Apply rate limiting and monitor traffic for anomalies.
Regularly test APIs against OWASP standards using tools like Qodex to automate vulnerability detection.
APIs are critical for modern software, but they also introduce unique security risks. 91% of organizations reported API security incidents in 2020, and attacks have only grown more frequent and severe. The OWASP API Security Top 10 is a framework designed to tackle these vulnerabilities, helping organizations secure APIs against threats like Broken Object Level Authorization (BOLA), Excessive Data Exposure, and Server-Side Request Forgery (SSRF).
Key Takeaways:
APIs now account for 83% of web traffic, making them prime attack targets.
The average cost of an API breach is $4.88 million, as seen in the 2023 T-Mobile breach impacting 37 million users.
OWASP’s framework highlights the top API risks, such as Broken Authentication, Security Misconfiguration, and Rate Limiting Failures.
To secure APIs:
Use strong authentication (OAuth 2.0, MFA) and authorization (RBAC).
Validate inputs, enforce server-side filtering, and limit data exposure.
Apply rate limiting and monitor traffic for anomalies.
Regularly test APIs against OWASP standards using tools like Qodex to automate vulnerability detection.
The OWASP API Security Top 10 Vulnerabilities Explained
Grasping the details behind each OWASP API Security Top 10 risk is essential for safeguarding sensitive data and securing APIs. These vulnerabilities represent common attack methods that can compromise your systems and expose private information. Let’s break down the key risks.
1. Broken Object Level Authorization
Broken Object Level Authorization (BOLA) happens when APIs fail to confirm whether a user has the proper permissions to access specific objects or resources. This flaw increases the risk by exposing endpoints tied to object identifiers.
The issue often stems from poor authorization checks, where APIs rely on client-supplied object IDs without verifying whether the user is allowed access. Instead of validating permissions, the API assumes the request is legitimate.
A notable example is the 2021 Peloton API flaw, which allowed users to view others' account details, exposing private information. This highlights how such oversights can jeopardize user privacy.
Attackers exploit this by manipulating object identifiers in requests to access, modify, or delete resources belonging to others. This can lead to severe privacy breaches and compliance problems, especially with regulated data like healthcare or financial records.
Risks of Broken Object Property Level Authorization
When APIs skip proper checks at the object property level, sensitive data can slip through the cracks—or worse, land in the wrong hands. Instead of verifying whether a user has the right to access or modify particular fields within an object, many APIs inadvertently trust any incoming request.
The result? Attackers may view or alter information they shouldn’t be able to—think exposed email addresses, account settings, or confidential financial details hidden deep within a user profile. Even seemingly harmless endpoints can be a goldmine for those savvy enough to craft requests targeting specific object properties.
If these validation gaps go unchecked, it can lead to:
Accidental leaks of private user data through excessive data exposure
Unauthorized edits to protected properties via mass assignment
Compliance headaches, especially around regulated data (such as healthcare records)
An open invitation for attackers looking to exploit overlooked API endpoints
Ultimately, overlooking property-level security doesn’t just threaten individual privacy—it can undermine the whole API ecosystem.
2. Broken Authentication
Authentication is the first barrier against unauthorized access, but broken authentication can make APIs vulnerable. These flaws arise from weak, misconfigured, or insecure authentication systems that fail to properly verify user identities.
"The authentication mechanism is an easy target for attackers since it's exposed to everyone." - OWASP
Common issues include weak passwords, lack of multi-factor authentication, and insufficient protection against brute-force attacks. Many organizations also struggle with secure token validation and session management, leaving exploitable gaps.
For instance, a 2018 USPS API flaw exposed account data for 60 million users by allowing authenticated users to bypass proper checks.
When authentication mechanisms fail, attackers can impersonate users, gain access to sensitive data, and carry out unauthorized actions. This vulnerability often serves as a gateway for more advanced attacks, emphasizing the need for strong authentication protocols.
3. Excessive Data Exposure
Excessive Data Exposure occurs when APIs send more data than necessary, relying on client-side filtering instead of enforcing server-side controls.
"APIs rely on clients to perform the data filtering." - OWASP
Developers often return full datasets to accommodate multiple clients with varying data needs, assuming clients will filter out unnecessary information. This approach overlooks the risks of sending excessive data over the network.
For example, a flaw in Twitter’s API allowed attackers to compile datasets of personal information, which were later sold on hacker forums.
This vulnerability highlights the importance of server-side filtering to prevent exposing sensitive data unnecessarily.
4. Security Misconfiguration
Security misconfiguration is a widespread but preventable issue in API security. It occurs when APIs are improperly configured, leaving them vulnerable through default settings, missing patches, or unnecessary features.
The problem often arises from incomplete security hardening across environments, outdated systems, or a lack of adherence to best practices during deployment. Many organizations fail to maintain consistent configurations across development, staging, and production environments.
In 2017, SVR Tracking’s misconfigured API exposed the data of over 500,000 tracking devices. More recently, in 2024, FleetSecure’s misconfiguration of the X-Api-Version header enabled attackers to inject malicious JNDI lookups, granting unauthorized access and command execution.
These examples show how misconfigurations can lead to anything from data leaks to full system compromise, stressing the need for proper configuration management.
5. Server-Side Request Forgery (SSRF)
Server-Side Request Forgery (SSRF) happens when APIs accept unvalidated user-supplied URLs to fetch remote resources, effectively turning the server into a tool for malicious requests.
SSRF often occurs when APIs allow URLs as input for retrieving external content like images or documents. Without proper validation, attackers can redirect these requests to internal systems, cloud metadata services, or other sensitive endpoints.
In 2020, a Shopify Exchange flaw enabled SSRF attacks that led to root access on certain containers. Similarly, the Capital One breach involved an SSRF vulnerability that exposed credentials, affecting over 100 million users.
SSRF is particularly dangerous because it can bypass network defenses like firewalls, granting access to internal systems that should remain inaccessible. This underscores its potential to compromise internal infrastructure.
6. Broken Function Level Authorization
Broken function level authorization arises when APIs fail to enforce the right checks between different user roles and privileges. This problem often stems from complex access structures—think layered administrative groups tangled up with standard users—where it’s unclear who can do what. In these situations, developers might forget to restrict administrative actions or sensitive functions, inadvertently making them accessible to anyone who knows the right endpoint.
Consider an API behind a retail platform like Shopify: if the API doesn’t properly distinguish between regular users and store admins, a crafty attacker could discover admin-only endpoints and trigger actions like viewing sales data, changing pricing, or managing inventory—all without the appropriate permissions.
In effect, these oversights let malicious actors “level up” in a system, hijacking functions or viewing data that should be walled off. This makes it crucial for API developers to implement strict server-side checks, ensuring each request is truly allowed for the user making it. Skipping this step is like handing out spare keys to your whole apartment building and hoping no one tries the penthouse door.
7. Risks of Unsafe Consumption of Third-Party APIs
Unsafe consumption of third-party APIs occurs when developers trust external APIs by default, skipping rigorous validation and security checks. This misplaced trust opens the door for attackers, who often target loosely defended integrations as a backdoor into otherwise secure systems.
The danger here is twofold. First, malicious actors can manipulate responses from poorly secured external APIs—think of payment processors, mapping services, or communication tools like Twilio and Slack—tricking your application into accepting tainted data or unauthorized requests. Second, if a popular third-party service is compromised, any application integrated with it could unintentionally inherit those risks.
Consider the case where a compromised weather data provider delivers malicious scripts or exposes sensitive configuration details. Attackers can leverage this indirect route to launch attacks, exfiltrate data, or gain access to privileged functions—all without having to breach the core API directly.
Ultimately, relying too heavily on external APIs without proper validation is like inviting strangers into your home and assuming they won’t steal your Wi-Fi password. Defensive coding, vigilant monitoring, and clear boundaries are essential to prevent abuse and avoid making your API the weakest link in a complex ecosystem.
Top API Security Risks in 2025
Understanding the primary threats to your APIs is key to building secure, modern applications. Here’s an overview of the most pressing API security risks developers and security teams should watch for this year:
Broken Object Level Authorization: Attackers exploit flaws in how APIs handle access to resources identified by user-supplied IDs. Without strict permission checks, it's possible for users to gain unauthorized access simply by tweaking object identifiers.
Broken Authentication: Weak or improperly implemented authentication lets attackers hijack tokens or session data—leading to account takeover and privacy violations. Ensuring robustness in authentication, like using OAuth 2.0 and MFA, is non-negotiable.
Broken Object Property Level Authorization: APIs sometimes fail to properly restrict access at the individual property level—leaking sensitive data or allowing users to modify fields they shouldn’t. Strong authorization validation is essential, both at the object and property layer.
Unrestricted Resource Consumption: APIs are gateways to system resources (bandwidth, CPU, messaging services). Too many unfiltered requests—malicious or otherwise—can drive up costs, impact performance, or trigger denial-of-service conditions.
Broken Function Level Authorization: Not all API functions are created equal. If there's no clear separation between admin and regular operations, attackers might escalate privileges and access functions meant for admins—exposing systems to critical misuse.
Unrestricted Access to Sensitive Business Flows: Some business processes (like ticket purchases or mass comments) are exposed via APIs without safeguards against automation. This can be abused for fraud, scalping, or spam, harming both users and the business itself.
Server-Side Request Forgery (SSRF): When APIs fetch remote resources without validating user-provided URLs, attackers can make your server act as a proxy—targeting internal systems or cloud metadata endpoints typically shielded from public access.
Security Misconfiguration: Complex configuration settings often lead to overlooked risks. Gaps in deployments or weak defaults open up vulnerabilities, so regular audits and adherence to best practices are critical.
Improper Inventory Management: Losing track of exposed endpoints, outdated API versions, or test/debug interfaces leads to shadow APIs and unnecessary attack surfaces. Keeping detailed, current documentation and inventories helps shut these doors.
Unsafe Consumption of Third-Party APIs: Trusting data from external APIs without proper scrutiny can introduce risks—supply chain weaknesses, weaker security standards, and indirect breaches might slip in through these integrations.
By recognizing these core risks, you can prioritize defenses and build APIs that stand resilient against modern threats.
Grasping the details behind each OWASP API Security Top 10 risk is essential for safeguarding sensitive data and securing APIs. These vulnerabilities represent common attack methods that can compromise your systems and expose private information. Let’s break down the key risks.
1. Broken Object Level Authorization
Broken Object Level Authorization (BOLA) happens when APIs fail to confirm whether a user has the proper permissions to access specific objects or resources. This flaw increases the risk by exposing endpoints tied to object identifiers.
The issue often stems from poor authorization checks, where APIs rely on client-supplied object IDs without verifying whether the user is allowed access. Instead of validating permissions, the API assumes the request is legitimate.
A notable example is the 2021 Peloton API flaw, which allowed users to view others' account details, exposing private information. This highlights how such oversights can jeopardize user privacy.
Attackers exploit this by manipulating object identifiers in requests to access, modify, or delete resources belonging to others. This can lead to severe privacy breaches and compliance problems, especially with regulated data like healthcare or financial records.
Risks of Broken Object Property Level Authorization
When APIs skip proper checks at the object property level, sensitive data can slip through the cracks—or worse, land in the wrong hands. Instead of verifying whether a user has the right to access or modify particular fields within an object, many APIs inadvertently trust any incoming request.
The result? Attackers may view or alter information they shouldn’t be able to—think exposed email addresses, account settings, or confidential financial details hidden deep within a user profile. Even seemingly harmless endpoints can be a goldmine for those savvy enough to craft requests targeting specific object properties.
If these validation gaps go unchecked, it can lead to:
Accidental leaks of private user data through excessive data exposure
Unauthorized edits to protected properties via mass assignment
Compliance headaches, especially around regulated data (such as healthcare records)
An open invitation for attackers looking to exploit overlooked API endpoints
Ultimately, overlooking property-level security doesn’t just threaten individual privacy—it can undermine the whole API ecosystem.
2. Broken Authentication
Authentication is the first barrier against unauthorized access, but broken authentication can make APIs vulnerable. These flaws arise from weak, misconfigured, or insecure authentication systems that fail to properly verify user identities.
"The authentication mechanism is an easy target for attackers since it's exposed to everyone." - OWASP
Common issues include weak passwords, lack of multi-factor authentication, and insufficient protection against brute-force attacks. Many organizations also struggle with secure token validation and session management, leaving exploitable gaps.
For instance, a 2018 USPS API flaw exposed account data for 60 million users by allowing authenticated users to bypass proper checks.
When authentication mechanisms fail, attackers can impersonate users, gain access to sensitive data, and carry out unauthorized actions. This vulnerability often serves as a gateway for more advanced attacks, emphasizing the need for strong authentication protocols.
3. Excessive Data Exposure
Excessive Data Exposure occurs when APIs send more data than necessary, relying on client-side filtering instead of enforcing server-side controls.
"APIs rely on clients to perform the data filtering." - OWASP
Developers often return full datasets to accommodate multiple clients with varying data needs, assuming clients will filter out unnecessary information. This approach overlooks the risks of sending excessive data over the network.
For example, a flaw in Twitter’s API allowed attackers to compile datasets of personal information, which were later sold on hacker forums.
This vulnerability highlights the importance of server-side filtering to prevent exposing sensitive data unnecessarily.
4. Security Misconfiguration
Security misconfiguration is a widespread but preventable issue in API security. It occurs when APIs are improperly configured, leaving them vulnerable through default settings, missing patches, or unnecessary features.
The problem often arises from incomplete security hardening across environments, outdated systems, or a lack of adherence to best practices during deployment. Many organizations fail to maintain consistent configurations across development, staging, and production environments.
In 2017, SVR Tracking’s misconfigured API exposed the data of over 500,000 tracking devices. More recently, in 2024, FleetSecure’s misconfiguration of the X-Api-Version header enabled attackers to inject malicious JNDI lookups, granting unauthorized access and command execution.
These examples show how misconfigurations can lead to anything from data leaks to full system compromise, stressing the need for proper configuration management.
5. Server-Side Request Forgery (SSRF)
Server-Side Request Forgery (SSRF) happens when APIs accept unvalidated user-supplied URLs to fetch remote resources, effectively turning the server into a tool for malicious requests.
SSRF often occurs when APIs allow URLs as input for retrieving external content like images or documents. Without proper validation, attackers can redirect these requests to internal systems, cloud metadata services, or other sensitive endpoints.
In 2020, a Shopify Exchange flaw enabled SSRF attacks that led to root access on certain containers. Similarly, the Capital One breach involved an SSRF vulnerability that exposed credentials, affecting over 100 million users.
SSRF is particularly dangerous because it can bypass network defenses like firewalls, granting access to internal systems that should remain inaccessible. This underscores its potential to compromise internal infrastructure.
6. Broken Function Level Authorization
Broken function level authorization arises when APIs fail to enforce the right checks between different user roles and privileges. This problem often stems from complex access structures—think layered administrative groups tangled up with standard users—where it’s unclear who can do what. In these situations, developers might forget to restrict administrative actions or sensitive functions, inadvertently making them accessible to anyone who knows the right endpoint.
Consider an API behind a retail platform like Shopify: if the API doesn’t properly distinguish between regular users and store admins, a crafty attacker could discover admin-only endpoints and trigger actions like viewing sales data, changing pricing, or managing inventory—all without the appropriate permissions.
In effect, these oversights let malicious actors “level up” in a system, hijacking functions or viewing data that should be walled off. This makes it crucial for API developers to implement strict server-side checks, ensuring each request is truly allowed for the user making it. Skipping this step is like handing out spare keys to your whole apartment building and hoping no one tries the penthouse door.
7. Risks of Unsafe Consumption of Third-Party APIs
Unsafe consumption of third-party APIs occurs when developers trust external APIs by default, skipping rigorous validation and security checks. This misplaced trust opens the door for attackers, who often target loosely defended integrations as a backdoor into otherwise secure systems.
The danger here is twofold. First, malicious actors can manipulate responses from poorly secured external APIs—think of payment processors, mapping services, or communication tools like Twilio and Slack—tricking your application into accepting tainted data or unauthorized requests. Second, if a popular third-party service is compromised, any application integrated with it could unintentionally inherit those risks.
Consider the case where a compromised weather data provider delivers malicious scripts or exposes sensitive configuration details. Attackers can leverage this indirect route to launch attacks, exfiltrate data, or gain access to privileged functions—all without having to breach the core API directly.
Ultimately, relying too heavily on external APIs without proper validation is like inviting strangers into your home and assuming they won’t steal your Wi-Fi password. Defensive coding, vigilant monitoring, and clear boundaries are essential to prevent abuse and avoid making your API the weakest link in a complex ecosystem.
Top API Security Risks in 2025
Understanding the primary threats to your APIs is key to building secure, modern applications. Here’s an overview of the most pressing API security risks developers and security teams should watch for this year:
Broken Object Level Authorization: Attackers exploit flaws in how APIs handle access to resources identified by user-supplied IDs. Without strict permission checks, it's possible for users to gain unauthorized access simply by tweaking object identifiers.
Broken Authentication: Weak or improperly implemented authentication lets attackers hijack tokens or session data—leading to account takeover and privacy violations. Ensuring robustness in authentication, like using OAuth 2.0 and MFA, is non-negotiable.
Broken Object Property Level Authorization: APIs sometimes fail to properly restrict access at the individual property level—leaking sensitive data or allowing users to modify fields they shouldn’t. Strong authorization validation is essential, both at the object and property layer.
Unrestricted Resource Consumption: APIs are gateways to system resources (bandwidth, CPU, messaging services). Too many unfiltered requests—malicious or otherwise—can drive up costs, impact performance, or trigger denial-of-service conditions.
Broken Function Level Authorization: Not all API functions are created equal. If there's no clear separation between admin and regular operations, attackers might escalate privileges and access functions meant for admins—exposing systems to critical misuse.
Unrestricted Access to Sensitive Business Flows: Some business processes (like ticket purchases or mass comments) are exposed via APIs without safeguards against automation. This can be abused for fraud, scalping, or spam, harming both users and the business itself.
Server-Side Request Forgery (SSRF): When APIs fetch remote resources without validating user-provided URLs, attackers can make your server act as a proxy—targeting internal systems or cloud metadata endpoints typically shielded from public access.
Security Misconfiguration: Complex configuration settings often lead to overlooked risks. Gaps in deployments or weak defaults open up vulnerabilities, so regular audits and adherence to best practices are critical.
Improper Inventory Management: Losing track of exposed endpoints, outdated API versions, or test/debug interfaces leads to shadow APIs and unnecessary attack surfaces. Keeping detailed, current documentation and inventories helps shut these doors.
Unsafe Consumption of Third-Party APIs: Trusting data from external APIs without proper scrutiny can introduce risks—supply chain weaknesses, weaker security standards, and indirect breaches might slip in through these integrations.
By recognizing these core risks, you can prioritize defenses and build APIs that stand resilient against modern threats.
Grasping the details behind each OWASP API Security Top 10 risk is essential for safeguarding sensitive data and securing APIs. These vulnerabilities represent common attack methods that can compromise your systems and expose private information. Let’s break down the key risks.
1. Broken Object Level Authorization
Broken Object Level Authorization (BOLA) happens when APIs fail to confirm whether a user has the proper permissions to access specific objects or resources. This flaw increases the risk by exposing endpoints tied to object identifiers.
The issue often stems from poor authorization checks, where APIs rely on client-supplied object IDs without verifying whether the user is allowed access. Instead of validating permissions, the API assumes the request is legitimate.
A notable example is the 2021 Peloton API flaw, which allowed users to view others' account details, exposing private information. This highlights how such oversights can jeopardize user privacy.
Attackers exploit this by manipulating object identifiers in requests to access, modify, or delete resources belonging to others. This can lead to severe privacy breaches and compliance problems, especially with regulated data like healthcare or financial records.
Risks of Broken Object Property Level Authorization
When APIs skip proper checks at the object property level, sensitive data can slip through the cracks—or worse, land in the wrong hands. Instead of verifying whether a user has the right to access or modify particular fields within an object, many APIs inadvertently trust any incoming request.
The result? Attackers may view or alter information they shouldn’t be able to—think exposed email addresses, account settings, or confidential financial details hidden deep within a user profile. Even seemingly harmless endpoints can be a goldmine for those savvy enough to craft requests targeting specific object properties.
If these validation gaps go unchecked, it can lead to:
Accidental leaks of private user data through excessive data exposure
Unauthorized edits to protected properties via mass assignment
Compliance headaches, especially around regulated data (such as healthcare records)
An open invitation for attackers looking to exploit overlooked API endpoints
Ultimately, overlooking property-level security doesn’t just threaten individual privacy—it can undermine the whole API ecosystem.
2. Broken Authentication
Authentication is the first barrier against unauthorized access, but broken authentication can make APIs vulnerable. These flaws arise from weak, misconfigured, or insecure authentication systems that fail to properly verify user identities.
"The authentication mechanism is an easy target for attackers since it's exposed to everyone." - OWASP
Common issues include weak passwords, lack of multi-factor authentication, and insufficient protection against brute-force attacks. Many organizations also struggle with secure token validation and session management, leaving exploitable gaps.
For instance, a 2018 USPS API flaw exposed account data for 60 million users by allowing authenticated users to bypass proper checks.
When authentication mechanisms fail, attackers can impersonate users, gain access to sensitive data, and carry out unauthorized actions. This vulnerability often serves as a gateway for more advanced attacks, emphasizing the need for strong authentication protocols.
3. Excessive Data Exposure
Excessive Data Exposure occurs when APIs send more data than necessary, relying on client-side filtering instead of enforcing server-side controls.
"APIs rely on clients to perform the data filtering." - OWASP
Developers often return full datasets to accommodate multiple clients with varying data needs, assuming clients will filter out unnecessary information. This approach overlooks the risks of sending excessive data over the network.
For example, a flaw in Twitter’s API allowed attackers to compile datasets of personal information, which were later sold on hacker forums.
This vulnerability highlights the importance of server-side filtering to prevent exposing sensitive data unnecessarily.
4. Security Misconfiguration
Security misconfiguration is a widespread but preventable issue in API security. It occurs when APIs are improperly configured, leaving them vulnerable through default settings, missing patches, or unnecessary features.
The problem often arises from incomplete security hardening across environments, outdated systems, or a lack of adherence to best practices during deployment. Many organizations fail to maintain consistent configurations across development, staging, and production environments.
In 2017, SVR Tracking’s misconfigured API exposed the data of over 500,000 tracking devices. More recently, in 2024, FleetSecure’s misconfiguration of the X-Api-Version header enabled attackers to inject malicious JNDI lookups, granting unauthorized access and command execution.
These examples show how misconfigurations can lead to anything from data leaks to full system compromise, stressing the need for proper configuration management.
5. Server-Side Request Forgery (SSRF)
Server-Side Request Forgery (SSRF) happens when APIs accept unvalidated user-supplied URLs to fetch remote resources, effectively turning the server into a tool for malicious requests.
SSRF often occurs when APIs allow URLs as input for retrieving external content like images or documents. Without proper validation, attackers can redirect these requests to internal systems, cloud metadata services, or other sensitive endpoints.
In 2020, a Shopify Exchange flaw enabled SSRF attacks that led to root access on certain containers. Similarly, the Capital One breach involved an SSRF vulnerability that exposed credentials, affecting over 100 million users.
SSRF is particularly dangerous because it can bypass network defenses like firewalls, granting access to internal systems that should remain inaccessible. This underscores its potential to compromise internal infrastructure.
6. Broken Function Level Authorization
Broken function level authorization arises when APIs fail to enforce the right checks between different user roles and privileges. This problem often stems from complex access structures—think layered administrative groups tangled up with standard users—where it’s unclear who can do what. In these situations, developers might forget to restrict administrative actions or sensitive functions, inadvertently making them accessible to anyone who knows the right endpoint.
Consider an API behind a retail platform like Shopify: if the API doesn’t properly distinguish between regular users and store admins, a crafty attacker could discover admin-only endpoints and trigger actions like viewing sales data, changing pricing, or managing inventory—all without the appropriate permissions.
In effect, these oversights let malicious actors “level up” in a system, hijacking functions or viewing data that should be walled off. This makes it crucial for API developers to implement strict server-side checks, ensuring each request is truly allowed for the user making it. Skipping this step is like handing out spare keys to your whole apartment building and hoping no one tries the penthouse door.
7. Risks of Unsafe Consumption of Third-Party APIs
Unsafe consumption of third-party APIs occurs when developers trust external APIs by default, skipping rigorous validation and security checks. This misplaced trust opens the door for attackers, who often target loosely defended integrations as a backdoor into otherwise secure systems.
The danger here is twofold. First, malicious actors can manipulate responses from poorly secured external APIs—think of payment processors, mapping services, or communication tools like Twilio and Slack—tricking your application into accepting tainted data or unauthorized requests. Second, if a popular third-party service is compromised, any application integrated with it could unintentionally inherit those risks.
Consider the case where a compromised weather data provider delivers malicious scripts or exposes sensitive configuration details. Attackers can leverage this indirect route to launch attacks, exfiltrate data, or gain access to privileged functions—all without having to breach the core API directly.
Ultimately, relying too heavily on external APIs without proper validation is like inviting strangers into your home and assuming they won’t steal your Wi-Fi password. Defensive coding, vigilant monitoring, and clear boundaries are essential to prevent abuse and avoid making your API the weakest link in a complex ecosystem.
Top API Security Risks in 2025
Understanding the primary threats to your APIs is key to building secure, modern applications. Here’s an overview of the most pressing API security risks developers and security teams should watch for this year:
Broken Object Level Authorization: Attackers exploit flaws in how APIs handle access to resources identified by user-supplied IDs. Without strict permission checks, it's possible for users to gain unauthorized access simply by tweaking object identifiers.
Broken Authentication: Weak or improperly implemented authentication lets attackers hijack tokens or session data—leading to account takeover and privacy violations. Ensuring robustness in authentication, like using OAuth 2.0 and MFA, is non-negotiable.
Broken Object Property Level Authorization: APIs sometimes fail to properly restrict access at the individual property level—leaking sensitive data or allowing users to modify fields they shouldn’t. Strong authorization validation is essential, both at the object and property layer.
Unrestricted Resource Consumption: APIs are gateways to system resources (bandwidth, CPU, messaging services). Too many unfiltered requests—malicious or otherwise—can drive up costs, impact performance, or trigger denial-of-service conditions.
Broken Function Level Authorization: Not all API functions are created equal. If there's no clear separation between admin and regular operations, attackers might escalate privileges and access functions meant for admins—exposing systems to critical misuse.
Unrestricted Access to Sensitive Business Flows: Some business processes (like ticket purchases or mass comments) are exposed via APIs without safeguards against automation. This can be abused for fraud, scalping, or spam, harming both users and the business itself.
Server-Side Request Forgery (SSRF): When APIs fetch remote resources without validating user-provided URLs, attackers can make your server act as a proxy—targeting internal systems or cloud metadata endpoints typically shielded from public access.
Security Misconfiguration: Complex configuration settings often lead to overlooked risks. Gaps in deployments or weak defaults open up vulnerabilities, so regular audits and adherence to best practices are critical.
Improper Inventory Management: Losing track of exposed endpoints, outdated API versions, or test/debug interfaces leads to shadow APIs and unnecessary attack surfaces. Keeping detailed, current documentation and inventories helps shut these doors.
Unsafe Consumption of Third-Party APIs: Trusting data from external APIs without proper scrutiny can introduce risks—supply chain weaknesses, weaker security standards, and indirect breaches might slip in through these integrations.
By recognizing these core risks, you can prioritize defenses and build APIs that stand resilient against modern threats.
How to Fix API Vulnerabilities
Fixing API vulnerabilities involves layering different security measures to safeguard against the OWASP Top 10 threats. Each layer addresses specific risks, working together to build a stronger defense.
Setting Up Strong Authentication and Authorization
Authentication confirms user identity, while authorization determines what actions they’re allowed to perform. To secure your API:
Use OAuth 2.0 and JWT for passwordless authentication.
Add Multi-Factor Authentication (MFA) for sensitive applications.
Implement Role-Based Access Control (RBAC) with the principle of least privilege, granting users only the permissions they need.
Ensure secure token management by:
Using HTTPS for all API calls.
Rotating tokens regularly.
Setting expiration policies.
Storing tokens securely.
These steps directly address Broken Authentication vulnerabilities outlined in the OWASP Top 10.
Once authentication is in place, the next step is to validate and sanitize all input data to block potential attack vectors.
Validating and Sanitizing Input Data
Input validation and sanitization are crucial for defending against injection attacks and data manipulation. Since most vulnerabilities stem from improper input handling, focus on these practices:
Use server-side validation as your main defense.
Prevent SQL injection by using parameterized queries and prepared statements.
Define strict input rules through whitelist validation, allowing only acceptable characters, formats, and values.
Sanitize output to block cross-site scripting (XSS) attacks by encoding special characters before including them in responses.
Here’s how to handle different input types effectively:
Input Type | Recommended Techniques | Example |
|---|---|---|
Regular Expressions, Email Validation |
| |
Password | String Length, Special Character Checks | At least 8 characters, including numbers and symbols |
Age | Range Validation | Must be between 18 and 65 |
Avoid exposing sensitive system details in error messages. Instead, use generic responses that inform users without revealing internal configurations or logic.
Additionally, remove unnecessary characters from inputs using regular expressions. For example, allow only alphanumeric characters or specific symbols to reduce the risk of harmful content entering your system.
With input validation secured, the next focus is on managing traffic to prevent abuse.
Applying Rate Limiting and Throttling
Rate limiting and throttling help protect APIs from misuse while maintaining reliable performance for legitimate users. Depending on your API’s needs, you can use different algorithms:
Fixed Window: Simple.
Sliding Window: Offers smoother control.
Token Bucket: Handles traffic bursts effectively.
Leaky Bucket: Ensures a steady flow of requests.
API gateways make it easier to enforce these rules and manage traffic centrally.
Set tiered rate limits based on endpoint type and usage patterns. For example:
Endpoint Type | Rate Limit (with Burst) | Reasoning |
|---|---|---|
File Upload/Download | 10/minute (burst: 15) | High resource consumption |
Read Operations | 1000/minute (burst: 1500) | Minimal resource impact |
Write Operations | 100/minute (burst: 150) | Moderate resource usage |
Search Queries | 300/minute (burst: 450) | CPU-intensive tasks |
Track metrics like request patterns, error rates, and server load to adjust limits dynamically. During peak times, dynamic rate limiting can reduce server load by up to 40% while maintaining availability.
Communicate rate limits clearly in API response headers. Include information such as X-RateLimit-Limit, X-RateLimit-Remaining, and X-RateLimit-Reset, so clients can monitor their usage and plan requests accordingly.
Use circuit breakers to prevent cascading failures in downstream services. If a service becomes overwhelmed, circuit breakers temporarily halt requests, giving the system time to recover.
Set appropriate time windows and block durations to manage abuse effectively. For example:
Use 15–60 minute windows for tracking requests.
Apply 5–30 minute blocks for temporary restrictions.
Implement 24-hour reset periods for usage quotas.
"API rate limiting is, in a nutshell, limiting access for people (and bots) to access the API based on the rules/policies set by the API's operator or owner." – DataDome [2]
Fixing API vulnerabilities involves layering different security measures to safeguard against the OWASP Top 10 threats. Each layer addresses specific risks, working together to build a stronger defense.
Setting Up Strong Authentication and Authorization
Authentication confirms user identity, while authorization determines what actions they’re allowed to perform. To secure your API:
Use OAuth 2.0 and JWT for passwordless authentication.
Add Multi-Factor Authentication (MFA) for sensitive applications.
Implement Role-Based Access Control (RBAC) with the principle of least privilege, granting users only the permissions they need.
Ensure secure token management by:
Using HTTPS for all API calls.
Rotating tokens regularly.
Setting expiration policies.
Storing tokens securely.
These steps directly address Broken Authentication vulnerabilities outlined in the OWASP Top 10.
Once authentication is in place, the next step is to validate and sanitize all input data to block potential attack vectors.
Validating and Sanitizing Input Data
Input validation and sanitization are crucial for defending against injection attacks and data manipulation. Since most vulnerabilities stem from improper input handling, focus on these practices:
Use server-side validation as your main defense.
Prevent SQL injection by using parameterized queries and prepared statements.
Define strict input rules through whitelist validation, allowing only acceptable characters, formats, and values.
Sanitize output to block cross-site scripting (XSS) attacks by encoding special characters before including them in responses.
Here’s how to handle different input types effectively:
Input Type | Recommended Techniques | Example |
|---|---|---|
Regular Expressions, Email Validation |
| |
Password | String Length, Special Character Checks | At least 8 characters, including numbers and symbols |
Age | Range Validation | Must be between 18 and 65 |
Avoid exposing sensitive system details in error messages. Instead, use generic responses that inform users without revealing internal configurations or logic.
Additionally, remove unnecessary characters from inputs using regular expressions. For example, allow only alphanumeric characters or specific symbols to reduce the risk of harmful content entering your system.
With input validation secured, the next focus is on managing traffic to prevent abuse.
Applying Rate Limiting and Throttling
Rate limiting and throttling help protect APIs from misuse while maintaining reliable performance for legitimate users. Depending on your API’s needs, you can use different algorithms:
Fixed Window: Simple.
Sliding Window: Offers smoother control.
Token Bucket: Handles traffic bursts effectively.
Leaky Bucket: Ensures a steady flow of requests.
API gateways make it easier to enforce these rules and manage traffic centrally.
Set tiered rate limits based on endpoint type and usage patterns. For example:
Endpoint Type | Rate Limit (with Burst) | Reasoning |
|---|---|---|
File Upload/Download | 10/minute (burst: 15) | High resource consumption |
Read Operations | 1000/minute (burst: 1500) | Minimal resource impact |
Write Operations | 100/minute (burst: 150) | Moderate resource usage |
Search Queries | 300/minute (burst: 450) | CPU-intensive tasks |
Track metrics like request patterns, error rates, and server load to adjust limits dynamically. During peak times, dynamic rate limiting can reduce server load by up to 40% while maintaining availability.
Communicate rate limits clearly in API response headers. Include information such as X-RateLimit-Limit, X-RateLimit-Remaining, and X-RateLimit-Reset, so clients can monitor their usage and plan requests accordingly.
Use circuit breakers to prevent cascading failures in downstream services. If a service becomes overwhelmed, circuit breakers temporarily halt requests, giving the system time to recover.
Set appropriate time windows and block durations to manage abuse effectively. For example:
Use 15–60 minute windows for tracking requests.
Apply 5–30 minute blocks for temporary restrictions.
Implement 24-hour reset periods for usage quotas.
"API rate limiting is, in a nutshell, limiting access for people (and bots) to access the API based on the rules/policies set by the API's operator or owner." – DataDome [2]
Fixing API vulnerabilities involves layering different security measures to safeguard against the OWASP Top 10 threats. Each layer addresses specific risks, working together to build a stronger defense.
Setting Up Strong Authentication and Authorization
Authentication confirms user identity, while authorization determines what actions they’re allowed to perform. To secure your API:
Use OAuth 2.0 and JWT for passwordless authentication.
Add Multi-Factor Authentication (MFA) for sensitive applications.
Implement Role-Based Access Control (RBAC) with the principle of least privilege, granting users only the permissions they need.
Ensure secure token management by:
Using HTTPS for all API calls.
Rotating tokens regularly.
Setting expiration policies.
Storing tokens securely.
These steps directly address Broken Authentication vulnerabilities outlined in the OWASP Top 10.
Once authentication is in place, the next step is to validate and sanitize all input data to block potential attack vectors.
Validating and Sanitizing Input Data
Input validation and sanitization are crucial for defending against injection attacks and data manipulation. Since most vulnerabilities stem from improper input handling, focus on these practices:
Use server-side validation as your main defense.
Prevent SQL injection by using parameterized queries and prepared statements.
Define strict input rules through whitelist validation, allowing only acceptable characters, formats, and values.
Sanitize output to block cross-site scripting (XSS) attacks by encoding special characters before including them in responses.
Here’s how to handle different input types effectively:
Input Type | Recommended Techniques | Example |
|---|---|---|
Regular Expressions, Email Validation |
| |
Password | String Length, Special Character Checks | At least 8 characters, including numbers and symbols |
Age | Range Validation | Must be between 18 and 65 |
Avoid exposing sensitive system details in error messages. Instead, use generic responses that inform users without revealing internal configurations or logic.
Additionally, remove unnecessary characters from inputs using regular expressions. For example, allow only alphanumeric characters or specific symbols to reduce the risk of harmful content entering your system.
With input validation secured, the next focus is on managing traffic to prevent abuse.
Applying Rate Limiting and Throttling
Rate limiting and throttling help protect APIs from misuse while maintaining reliable performance for legitimate users. Depending on your API’s needs, you can use different algorithms:
Fixed Window: Simple.
Sliding Window: Offers smoother control.
Token Bucket: Handles traffic bursts effectively.
Leaky Bucket: Ensures a steady flow of requests.
API gateways make it easier to enforce these rules and manage traffic centrally.
Set tiered rate limits based on endpoint type and usage patterns. For example:
Endpoint Type | Rate Limit (with Burst) | Reasoning |
|---|---|---|
File Upload/Download | 10/minute (burst: 15) | High resource consumption |
Read Operations | 1000/minute (burst: 1500) | Minimal resource impact |
Write Operations | 100/minute (burst: 150) | Moderate resource usage |
Search Queries | 300/minute (burst: 450) | CPU-intensive tasks |
Track metrics like request patterns, error rates, and server load to adjust limits dynamically. During peak times, dynamic rate limiting can reduce server load by up to 40% while maintaining availability.
Communicate rate limits clearly in API response headers. Include information such as X-RateLimit-Limit, X-RateLimit-Remaining, and X-RateLimit-Reset, so clients can monitor their usage and plan requests accordingly.
Use circuit breakers to prevent cascading failures in downstream services. If a service becomes overwhelmed, circuit breakers temporarily halt requests, giving the system time to recover.
Set appropriate time windows and block durations to manage abuse effectively. For example:
Use 15–60 minute windows for tracking requests.
Apply 5–30 minute blocks for temporary restrictions.
Implement 24-hour reset periods for usage quotas.
"API rate limiting is, in a nutshell, limiting access for people (and bots) to access the API based on the rules/policies set by the API's operator or owner." – DataDome [2]
Using AI-Powered API Security Tools with Qodex
To ensure long-term protection for your APIs, it's essential to establish a structured security program based on OWASP standards. With 84% of organizations experiencing API security incidents in the last year, this isn't just a precaution - it's a necessity.
"APIs are the backbone of today's digital world, connecting everything from fintech apps to smart home gadgets. With APIs powering virtually every digital experience, knowing how to set up an API security framework isn't just nice-to-have - it's make-or-break for your business."
Adrian Machado, Staff Engineer [9]
Below, we’ll explore actionable steps to build and maintain a strong API security program.
Initial Risk Assessment and API Inventory
The first step in securing your APIs is understanding what you're protecting. Despite APIs driving much of today’s traffic, many organizations struggle to identify which endpoints expose sensitive data. This lack of visibility creates major security risks.
Start by using automated tools to locate undocumented APIs that may have been deployed without formal oversight. Catalog every API endpoint, noting its purpose, the data it processes, and its current security status. This inventory forms the foundation of your security efforts.
Proper and updated documentation is equally important—APIs tend to expose far more endpoints than traditional web apps, so gaps in inventory or outdated documentation can leave you blind to risks. Maintain a living inventory not just of endpoints, but also of deployed hosts and API versions. Keeping track of deprecated versions, exposed debug endpoints, and shadow APIs prevents attackers from exploiting forgotten or under-secured interfaces.With a complete, accurate inventory and documentation in place, you’ll be better equipped to identify vulnerabilities, decommission outdated endpoints, and ensure your APIs evolve securely over time.
As you document and assess your APIs, pay special attention to endpoints that expose entire business flows—such as ticket purchasing, comment posting, or financial transactions. APIs that lack proper controls around these flows can be particularly vulnerable to abuse, such as automated attacks that exploit the business logic rather than traditional implementation bugs. For example, if an attacker can rapidly purchase tickets or flood your application with automated comments, the business impact can be significant—even if your authentication and validation are technically sound.
As you assess your API landscape, pay particular attention to business flows that could be abused at scale even if they aren’t directly vulnerable due to a coding bug. For example, APIs that allow users to purchase tickets, submit reviews, or perform actions that affect your business should be evaluated for how they might be exploited through automation. Exposing these flows without proper controls—such as rate limiting, behavioral analytics, or CAPTCHA—can open the door to significant business risks, including fraud and service disruption. Remember, not all threats stem from technical vulnerabilities; sometimes it’s the lack of compensating controls that exposes your business to harm.
Why inventory matters:
APIs tend to expose more endpoints than traditional web applications, making proper and updated documentation absolutely essential. Without a comprehensive and current inventory—including all hosts, deployed versions, and environments—it’s alarmingly easy for deprecated endpoints or forgotten debug APIs to slip through the cracks. These overlooked or outdated endpoints can become easy targets for attackers, as they’re often less monitored and may lack up-to-date security controls.
Be thorough:
Document every host and deployed API version.
Regularly update your inventory as APIs evolve, are versioned, or retired.
Ensure all endpoints, including staging, development, and debug points, are accounted for.
A robust, well-maintained API inventory not only helps mitigate risks from obsolete or exposed endpoints, but also sets the stage for effective risk assessment and vulnerability management.
Next, perform a gap analysis by comparing your current security measures against the OWASP API Top 10. This analysis should flag issues like missing authentication, excessive data exposure, or insufficient logging. Once identified, prioritize vulnerabilities based on the sensitivity of the data involved and the potential business impact.
To make the case for investing in API security, quantify the risks. Highlight the potential costs of a breach - such as regulatory penalties, loss of customer trust, and operational downtime - against the expense of implementing stronger security measures. This approach can help clarify the return on investment for stakeholders.
Adding Security to Development Workflows
After assessing risks and documenting APIs, it’s time to embed security into your development process. Security should be a core part of your workflows from the start, not an afterthought. For example, every pull request can trigger automated security scans to catch vulnerabilities early.
Here are some best practices to adopt:
Use OAuth 2.0: Employ short-lived access tokens (15–30 minutes) with refresh tokens to balance security with user convenience.
Set Rate Limits: Tailor rate-limiting rules to the behavior of each endpoint. For instance, authentication endpoints may require stricter limits than others.
Define Data Retention Policies: Limit data storage to reduce exposure. This applies to user data, logs, cached responses, and temporary files.
Automate Security Testing: Integrate automated scans into your CI/CD pipeline. Regularly test against the OWASP Top 10 to ensure new code doesn’t introduce vulnerabilities.
Continuous Improvement and Incident Response
Maintaining a strong API security posture requires ongoing monitoring and preparation for incidents. Preventive measures alone aren’t enough - you also need to detect and respond to threats in real time.
Monitor Traffic: Use real-time monitoring to identify unusual activity, such as unexpected data access or high request volumes.
Implement Comprehensive Logging: Create audit trails that capture authentication events, data access patterns, errors, and security violations. These logs are invaluable for investigations and compliance.
Establish Incident Response Plans: Develop step-by-step procedures for handling common API security incidents, such as data breaches or denial-of-service attacks. Assign roles, define communication channels, and outline recovery steps to ensure a quick, coordinated response.
To keep your defenses sharp, conduct regular security audits and penetration tests. Ethical hackers or automated tools can simulate real-world attacks to uncover weaknesses in your system.
Finally, invest in ongoing education for your teams. Provide training on secure coding practices, input validation, and other API security essentials, using examples specific to your tech stack. Regularly update these sessions to address new threats and industry developments.
"We're certainly in the early days of this emerging API security space, but in thinking about API security going forward, it's going to become the very foundation for modern applications."
Tyler Reynolds, Senior Solution Architect at Kong and Channel & GTM Director at Traceable.ai [11]
To ensure long-term protection for your APIs, it's essential to establish a structured security program based on OWASP standards. With 84% of organizations experiencing API security incidents in the last year, this isn't just a precaution - it's a necessity.
"APIs are the backbone of today's digital world, connecting everything from fintech apps to smart home gadgets. With APIs powering virtually every digital experience, knowing how to set up an API security framework isn't just nice-to-have - it's make-or-break for your business."
Adrian Machado, Staff Engineer [9]
Below, we’ll explore actionable steps to build and maintain a strong API security program.
Initial Risk Assessment and API Inventory
The first step in securing your APIs is understanding what you're protecting. Despite APIs driving much of today’s traffic, many organizations struggle to identify which endpoints expose sensitive data. This lack of visibility creates major security risks.
Start by using automated tools to locate undocumented APIs that may have been deployed without formal oversight. Catalog every API endpoint, noting its purpose, the data it processes, and its current security status. This inventory forms the foundation of your security efforts.
Proper and updated documentation is equally important—APIs tend to expose far more endpoints than traditional web apps, so gaps in inventory or outdated documentation can leave you blind to risks. Maintain a living inventory not just of endpoints, but also of deployed hosts and API versions. Keeping track of deprecated versions, exposed debug endpoints, and shadow APIs prevents attackers from exploiting forgotten or under-secured interfaces.With a complete, accurate inventory and documentation in place, you’ll be better equipped to identify vulnerabilities, decommission outdated endpoints, and ensure your APIs evolve securely over time.
As you document and assess your APIs, pay special attention to endpoints that expose entire business flows—such as ticket purchasing, comment posting, or financial transactions. APIs that lack proper controls around these flows can be particularly vulnerable to abuse, such as automated attacks that exploit the business logic rather than traditional implementation bugs. For example, if an attacker can rapidly purchase tickets or flood your application with automated comments, the business impact can be significant—even if your authentication and validation are technically sound.
As you assess your API landscape, pay particular attention to business flows that could be abused at scale even if they aren’t directly vulnerable due to a coding bug. For example, APIs that allow users to purchase tickets, submit reviews, or perform actions that affect your business should be evaluated for how they might be exploited through automation. Exposing these flows without proper controls—such as rate limiting, behavioral analytics, or CAPTCHA—can open the door to significant business risks, including fraud and service disruption. Remember, not all threats stem from technical vulnerabilities; sometimes it’s the lack of compensating controls that exposes your business to harm.
Why inventory matters:
APIs tend to expose more endpoints than traditional web applications, making proper and updated documentation absolutely essential. Without a comprehensive and current inventory—including all hosts, deployed versions, and environments—it’s alarmingly easy for deprecated endpoints or forgotten debug APIs to slip through the cracks. These overlooked or outdated endpoints can become easy targets for attackers, as they’re often less monitored and may lack up-to-date security controls.
Be thorough:
Document every host and deployed API version.
Regularly update your inventory as APIs evolve, are versioned, or retired.
Ensure all endpoints, including staging, development, and debug points, are accounted for.
A robust, well-maintained API inventory not only helps mitigate risks from obsolete or exposed endpoints, but also sets the stage for effective risk assessment and vulnerability management.
Next, perform a gap analysis by comparing your current security measures against the OWASP API Top 10. This analysis should flag issues like missing authentication, excessive data exposure, or insufficient logging. Once identified, prioritize vulnerabilities based on the sensitivity of the data involved and the potential business impact.
To make the case for investing in API security, quantify the risks. Highlight the potential costs of a breach - such as regulatory penalties, loss of customer trust, and operational downtime - against the expense of implementing stronger security measures. This approach can help clarify the return on investment for stakeholders.
Adding Security to Development Workflows
After assessing risks and documenting APIs, it’s time to embed security into your development process. Security should be a core part of your workflows from the start, not an afterthought. For example, every pull request can trigger automated security scans to catch vulnerabilities early.
Here are some best practices to adopt:
Use OAuth 2.0: Employ short-lived access tokens (15–30 minutes) with refresh tokens to balance security with user convenience.
Set Rate Limits: Tailor rate-limiting rules to the behavior of each endpoint. For instance, authentication endpoints may require stricter limits than others.
Define Data Retention Policies: Limit data storage to reduce exposure. This applies to user data, logs, cached responses, and temporary files.
Automate Security Testing: Integrate automated scans into your CI/CD pipeline. Regularly test against the OWASP Top 10 to ensure new code doesn’t introduce vulnerabilities.
Continuous Improvement and Incident Response
Maintaining a strong API security posture requires ongoing monitoring and preparation for incidents. Preventive measures alone aren’t enough - you also need to detect and respond to threats in real time.
Monitor Traffic: Use real-time monitoring to identify unusual activity, such as unexpected data access or high request volumes.
Implement Comprehensive Logging: Create audit trails that capture authentication events, data access patterns, errors, and security violations. These logs are invaluable for investigations and compliance.
Establish Incident Response Plans: Develop step-by-step procedures for handling common API security incidents, such as data breaches or denial-of-service attacks. Assign roles, define communication channels, and outline recovery steps to ensure a quick, coordinated response.
To keep your defenses sharp, conduct regular security audits and penetration tests. Ethical hackers or automated tools can simulate real-world attacks to uncover weaknesses in your system.
Finally, invest in ongoing education for your teams. Provide training on secure coding practices, input validation, and other API security essentials, using examples specific to your tech stack. Regularly update these sessions to address new threats and industry developments.
"We're certainly in the early days of this emerging API security space, but in thinking about API security going forward, it's going to become the very foundation for modern applications."
Tyler Reynolds, Senior Solution Architect at Kong and Channel & GTM Director at Traceable.ai [11]
To ensure long-term protection for your APIs, it's essential to establish a structured security program based on OWASP standards. With 84% of organizations experiencing API security incidents in the last year, this isn't just a precaution - it's a necessity.
"APIs are the backbone of today's digital world, connecting everything from fintech apps to smart home gadgets. With APIs powering virtually every digital experience, knowing how to set up an API security framework isn't just nice-to-have - it's make-or-break for your business."
Adrian Machado, Staff Engineer [9]
Below, we’ll explore actionable steps to build and maintain a strong API security program.
Initial Risk Assessment and API Inventory
The first step in securing your APIs is understanding what you're protecting. Despite APIs driving much of today’s traffic, many organizations struggle to identify which endpoints expose sensitive data. This lack of visibility creates major security risks.
Start by using automated tools to locate undocumented APIs that may have been deployed without formal oversight. Catalog every API endpoint, noting its purpose, the data it processes, and its current security status. This inventory forms the foundation of your security efforts.
Proper and updated documentation is equally important—APIs tend to expose far more endpoints than traditional web apps, so gaps in inventory or outdated documentation can leave you blind to risks. Maintain a living inventory not just of endpoints, but also of deployed hosts and API versions. Keeping track of deprecated versions, exposed debug endpoints, and shadow APIs prevents attackers from exploiting forgotten or under-secured interfaces.With a complete, accurate inventory and documentation in place, you’ll be better equipped to identify vulnerabilities, decommission outdated endpoints, and ensure your APIs evolve securely over time.
As you document and assess your APIs, pay special attention to endpoints that expose entire business flows—such as ticket purchasing, comment posting, or financial transactions. APIs that lack proper controls around these flows can be particularly vulnerable to abuse, such as automated attacks that exploit the business logic rather than traditional implementation bugs. For example, if an attacker can rapidly purchase tickets or flood your application with automated comments, the business impact can be significant—even if your authentication and validation are technically sound.
As you assess your API landscape, pay particular attention to business flows that could be abused at scale even if they aren’t directly vulnerable due to a coding bug. For example, APIs that allow users to purchase tickets, submit reviews, or perform actions that affect your business should be evaluated for how they might be exploited through automation. Exposing these flows without proper controls—such as rate limiting, behavioral analytics, or CAPTCHA—can open the door to significant business risks, including fraud and service disruption. Remember, not all threats stem from technical vulnerabilities; sometimes it’s the lack of compensating controls that exposes your business to harm.
Why inventory matters:
APIs tend to expose more endpoints than traditional web applications, making proper and updated documentation absolutely essential. Without a comprehensive and current inventory—including all hosts, deployed versions, and environments—it’s alarmingly easy for deprecated endpoints or forgotten debug APIs to slip through the cracks. These overlooked or outdated endpoints can become easy targets for attackers, as they’re often less monitored and may lack up-to-date security controls.
Be thorough:
Document every host and deployed API version.
Regularly update your inventory as APIs evolve, are versioned, or retired.
Ensure all endpoints, including staging, development, and debug points, are accounted for.
A robust, well-maintained API inventory not only helps mitigate risks from obsolete or exposed endpoints, but also sets the stage for effective risk assessment and vulnerability management.
Next, perform a gap analysis by comparing your current security measures against the OWASP API Top 10. This analysis should flag issues like missing authentication, excessive data exposure, or insufficient logging. Once identified, prioritize vulnerabilities based on the sensitivity of the data involved and the potential business impact.
To make the case for investing in API security, quantify the risks. Highlight the potential costs of a breach - such as regulatory penalties, loss of customer trust, and operational downtime - against the expense of implementing stronger security measures. This approach can help clarify the return on investment for stakeholders.
Adding Security to Development Workflows
After assessing risks and documenting APIs, it’s time to embed security into your development process. Security should be a core part of your workflows from the start, not an afterthought. For example, every pull request can trigger automated security scans to catch vulnerabilities early.
Here are some best practices to adopt:
Use OAuth 2.0: Employ short-lived access tokens (15–30 minutes) with refresh tokens to balance security with user convenience.
Set Rate Limits: Tailor rate-limiting rules to the behavior of each endpoint. For instance, authentication endpoints may require stricter limits than others.
Define Data Retention Policies: Limit data storage to reduce exposure. This applies to user data, logs, cached responses, and temporary files.
Automate Security Testing: Integrate automated scans into your CI/CD pipeline. Regularly test against the OWASP Top 10 to ensure new code doesn’t introduce vulnerabilities.
Continuous Improvement and Incident Response
Maintaining a strong API security posture requires ongoing monitoring and preparation for incidents. Preventive measures alone aren’t enough - you also need to detect and respond to threats in real time.
Monitor Traffic: Use real-time monitoring to identify unusual activity, such as unexpected data access or high request volumes.
Implement Comprehensive Logging: Create audit trails that capture authentication events, data access patterns, errors, and security violations. These logs are invaluable for investigations and compliance.
Establish Incident Response Plans: Develop step-by-step procedures for handling common API security incidents, such as data breaches or denial-of-service attacks. Assign roles, define communication channels, and outline recovery steps to ensure a quick, coordinated response.
To keep your defenses sharp, conduct regular security audits and penetration tests. Ethical hackers or automated tools can simulate real-world attacks to uncover weaknesses in your system.
Finally, invest in ongoing education for your teams. Provide training on secure coding practices, input validation, and other API security essentials, using examples specific to your tech stack. Regularly update these sessions to address new threats and industry developments.
"We're certainly in the early days of this emerging API security space, but in thinking about API security going forward, it's going to become the very foundation for modern applications."
Tyler Reynolds, Senior Solution Architect at Kong and Channel & GTM Director at Traceable.ai [11]
Conclusion: Key Points for API Security
API security is essential for safeguarding your digital systems against increasingly sophisticated threats. With API attacks surging by over 300% year-over-year and broken object-level authorization responsible for most reported API breaches, addressing the OWASP API Security Top 10 should be a top priority.
Real-world breaches often exploit vulnerabilities like manipulating object IDs or exposing excessive data. To counteract these risks, robust authentication and authorization measures are critical. This includes multi-factor authentication, secure session management, and strict access controls. In addition to strong authentication and authorization, it's vital to consider the resources your API consumes with each request—think network bandwidth, CPU, memory, storage, and even ancillary services like emails, SMS, or phone verification. If left unchecked, unrestricted resource consumption can leave your APIs open to denial-of-service attacks or unexpected spikes in operational costs that can catch your team off guard.
Additionally, strategies like rate limiting, resource quotas, and API throttling can mitigate denial-of-service attacks, ensuring your APIs remain accessible to legitimate users even during an assault.
These practical controls help prevent a single client—or a malicious actor—from overwhelming your infrastructure, while also protecting your bottom line from runaway usage fees. Satisfying API requests consumes valuable resources—network bandwidth, CPU, memory, and storage. Some service providers even extend resource-intensive features, such as sending emails, SMS, or performing biometric validation, via API integrations—often with a cost incurred per request. If left unchecked, attackers can abuse these endpoints, driving up operational expenses or overwhelming your infrastructure. By proactively controlling resource allocation and enforcing usage limits, you protect both your system’s performance and your bottom line. These proactive steps lay the groundwork for integrating automated security solutions.
Given the complexity of modern API environments, manual testing alone is no longer sufficient. Automated tools, such as DAST and AI-powered platforms, play a key role in identifying and addressing vulnerabilities in real time. Gartner forecasts that by 2025, more than half of data theft incidents will originate from unsecured APIs. Tools like Qodex streamline this process by automating vulnerability detection, enabling no-code testing for OWASP scenarios, and integrating seamlessly into CI/CD pipelines. This allows teams to catch and resolve security issues early in development, maintain compliance, and minimize the risks associated with manual testing.
API security is not a one-time effort - it requires ongoing vigilance. Regular audits, updated documentation, and proactive threat detection are vital. Practices like input validation and adhering to the principle of least privilege help minimize risks by ensuring sensitive data is only accessible to authorized users. Common issues, such as security misconfiguration and poor inventory management, can be addressed by keeping documentation current, following established best practices, and automating configuration checks.
The OWASP API Security Top 10 evolves regularly to address new threats and attack methods. Staying informed about these updates is crucial for maintaining a strong security posture. By applying the strategies discussed in this guide and leveraging modern security tools, you can create a resilient defense against the API vulnerabilities that could jeopardize your organization's data and reputation.
API security is essential for safeguarding your digital systems against increasingly sophisticated threats. With API attacks surging by over 300% year-over-year and broken object-level authorization responsible for most reported API breaches, addressing the OWASP API Security Top 10 should be a top priority.
Real-world breaches often exploit vulnerabilities like manipulating object IDs or exposing excessive data. To counteract these risks, robust authentication and authorization measures are critical. This includes multi-factor authentication, secure session management, and strict access controls. In addition to strong authentication and authorization, it's vital to consider the resources your API consumes with each request—think network bandwidth, CPU, memory, storage, and even ancillary services like emails, SMS, or phone verification. If left unchecked, unrestricted resource consumption can leave your APIs open to denial-of-service attacks or unexpected spikes in operational costs that can catch your team off guard.
Additionally, strategies like rate limiting, resource quotas, and API throttling can mitigate denial-of-service attacks, ensuring your APIs remain accessible to legitimate users even during an assault.
These practical controls help prevent a single client—or a malicious actor—from overwhelming your infrastructure, while also protecting your bottom line from runaway usage fees. Satisfying API requests consumes valuable resources—network bandwidth, CPU, memory, and storage. Some service providers even extend resource-intensive features, such as sending emails, SMS, or performing biometric validation, via API integrations—often with a cost incurred per request. If left unchecked, attackers can abuse these endpoints, driving up operational expenses or overwhelming your infrastructure. By proactively controlling resource allocation and enforcing usage limits, you protect both your system’s performance and your bottom line. These proactive steps lay the groundwork for integrating automated security solutions.
Given the complexity of modern API environments, manual testing alone is no longer sufficient. Automated tools, such as DAST and AI-powered platforms, play a key role in identifying and addressing vulnerabilities in real time. Gartner forecasts that by 2025, more than half of data theft incidents will originate from unsecured APIs. Tools like Qodex streamline this process by automating vulnerability detection, enabling no-code testing for OWASP scenarios, and integrating seamlessly into CI/CD pipelines. This allows teams to catch and resolve security issues early in development, maintain compliance, and minimize the risks associated with manual testing.
API security is not a one-time effort - it requires ongoing vigilance. Regular audits, updated documentation, and proactive threat detection are vital. Practices like input validation and adhering to the principle of least privilege help minimize risks by ensuring sensitive data is only accessible to authorized users. Common issues, such as security misconfiguration and poor inventory management, can be addressed by keeping documentation current, following established best practices, and automating configuration checks.
The OWASP API Security Top 10 evolves regularly to address new threats and attack methods. Staying informed about these updates is crucial for maintaining a strong security posture. By applying the strategies discussed in this guide and leveraging modern security tools, you can create a resilient defense against the API vulnerabilities that could jeopardize your organization's data and reputation.
API security is essential for safeguarding your digital systems against increasingly sophisticated threats. With API attacks surging by over 300% year-over-year and broken object-level authorization responsible for most reported API breaches, addressing the OWASP API Security Top 10 should be a top priority.
Real-world breaches often exploit vulnerabilities like manipulating object IDs or exposing excessive data. To counteract these risks, robust authentication and authorization measures are critical. This includes multi-factor authentication, secure session management, and strict access controls. In addition to strong authentication and authorization, it's vital to consider the resources your API consumes with each request—think network bandwidth, CPU, memory, storage, and even ancillary services like emails, SMS, or phone verification. If left unchecked, unrestricted resource consumption can leave your APIs open to denial-of-service attacks or unexpected spikes in operational costs that can catch your team off guard.
Additionally, strategies like rate limiting, resource quotas, and API throttling can mitigate denial-of-service attacks, ensuring your APIs remain accessible to legitimate users even during an assault.
These practical controls help prevent a single client—or a malicious actor—from overwhelming your infrastructure, while also protecting your bottom line from runaway usage fees. Satisfying API requests consumes valuable resources—network bandwidth, CPU, memory, and storage. Some service providers even extend resource-intensive features, such as sending emails, SMS, or performing biometric validation, via API integrations—often with a cost incurred per request. If left unchecked, attackers can abuse these endpoints, driving up operational expenses or overwhelming your infrastructure. By proactively controlling resource allocation and enforcing usage limits, you protect both your system’s performance and your bottom line. These proactive steps lay the groundwork for integrating automated security solutions.
Given the complexity of modern API environments, manual testing alone is no longer sufficient. Automated tools, such as DAST and AI-powered platforms, play a key role in identifying and addressing vulnerabilities in real time. Gartner forecasts that by 2025, more than half of data theft incidents will originate from unsecured APIs. Tools like Qodex streamline this process by automating vulnerability detection, enabling no-code testing for OWASP scenarios, and integrating seamlessly into CI/CD pipelines. This allows teams to catch and resolve security issues early in development, maintain compliance, and minimize the risks associated with manual testing.
API security is not a one-time effort - it requires ongoing vigilance. Regular audits, updated documentation, and proactive threat detection are vital. Practices like input validation and adhering to the principle of least privilege help minimize risks by ensuring sensitive data is only accessible to authorized users. Common issues, such as security misconfiguration and poor inventory management, can be addressed by keeping documentation current, following established best practices, and automating configuration checks.
The OWASP API Security Top 10 evolves regularly to address new threats and attack methods. Staying informed about these updates is crucial for maintaining a strong security posture. By applying the strategies discussed in this guide and leveraging modern security tools, you can create a resilient defense against the API vulnerabilities that could jeopardize your organization's data and reputation.
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