Introduction

Application Programming Interfaces (APIs) are now the foundation of contemporary software in the age of digital transformation. APIs provide smooth system-to-system communication from web platforms and mobile apps to IoT devices and microservices architectures. But enormous power also carries a huge deal of responsibility and a large attack surface. Because of their usefulness, accessibility, and frequently inadequate security measures, APIs are becoming more and more popular targets for cybercriminals.

The top API-related CVEs from 2024 and 2025, real-world examples, how hackers attack APIs, and—most importantly—how to protect your APIs from these dangers are all covered in detail in this comprehensive guide.

Why APIs Are Attractive Targets for Hackers

1. Data Exposure: PII, financial records, and business logic are examples of sensitive data frequently made public using APIs.
2. Ease of Access: Usually facing the internet, APIs provide attackers with convenient access points.
3. Overprivileged Endpoints: Access to more data than necessary may be made possible via poor design.
4. Authentication Weaknesses: Broken or absent authentication mechanisms.
5. Rate Limiting Issues: Abuse may result from a lack of throttling measures.

The Anatomy of an API Abuse Attack Hackers often follow a structured process to exploit APIs:

1. Reconnaissance: Studying API documentation, network traffic, and public information to identify weaknesses.
2. Authentication Bypass: Exploiting weak authentication mechanisms or logic flaws to gain unauthorized access.
3. Endpoint Enumeration: Systematically scanning endpoints to identify exploitable functionalities.
4. Parameter Manipulation: Altering input fields or payloads to exploit vulnerabilities like SQL injection or JSON injection.
5. Data Exfiltration: Extracting sensitive data such as user credentials or financial information.
6. Covering Tracks: Obfuscating activities by deleting logs or blending malicious traffic with legitimate requests.

Common Techniques Hackers Use to Exploit APIs

       1. Broken Object Level Authorization (BOLA)
           Attackers manipulate object IDs in API requests to access data belonging to other users.
           Example: Changing /api/user/12345/orders to /api/user/54321/orders to retrieve someone else’s orders.
       2. Mass Assignment
           Sending additional parameters in an API request to update fields that should not be user-controllable.
           Example: Using a PUT request to update the isAdmin property: { “username”: “john”, “isAdmin”: true }
       3. Insecure Endpoints
           APIs exposed without authentication or with hardcoded keys allow unauthorized access.
       4. Injection Attacks
           APIs are vulnerable to SQL, NoSQL, command injection, or LDAP injection when input is not sanitized.
       5. Improper Rate Limiting
           Lack of rate limiting allows brute-force attacks or resource exhaustion (DoS).
       6. Excessive Data Exposure
           Returning entire objects rather than specific fields.
       7. Security Misconfigurations
           Leaving debug mode on, exposing Swagger docs in production, or failing to disable unused HTTP methods.
       8. Replay Attacks
           Reusing valid requests to gain access without reauthentication.

Case Studies of API Breaches

• Case Study 1: Facebook (2018) – A vulnerability in Facebook’s API allowed attackers to harvest user access tokens and hijack accounts.
• Case Study 2: T-Mobile (2023) – An exposed API allowed attackers to access customer data, including billing addresses and phone numbers.
• Case Study 3: SolarWinds (2024) – APIs exposed via a misconfigured gateway enabled lateral movement and system compromise.

Top 10 API-Related CVEs in 2024 and 2025
Here are the top CVEs that affected API endpoints over the past two years:

CVE-2024-1222 | Critical | 9.8
This allows attackers to use a maliciously formed API request to gain access to an API authorization level with elevated privileges. This applies to a small subset of PaperCut NG/MF API calls.

CVE-2024-39864 | Critical | 9.8
The CloudStack integration API service, when disabled (default value 0), improperly listens on a random port, allowing attackers to exploit it for unauthorized administrative actions and remote code execution, compromising infrastructure confidentiality, integrity, and availability.

CVE-2025-31481 | High | 7.5
API Platform Core is a system to create hypermedia-driven REST and GraphQL APIs. Using the Relay special node type you can bypass the configured security on an operation.

CVE-2025-31485 | High | 7.5
API Platform Core is a system to create hypermedia-driven REST and GraphQL APIs. Prior to 4.0.22 and 3.4.17, a GraphQL grant on a property might be cached with different objects. The ApiPlatform\GraphQl\Serializer\ItemNormalizer::isCacheKeySafe() method is meant to prevent the caching but the parent::normalize method that is called afterwards still creates the cache key and causes the issue.

CVE-2024-45229 | Medium | 6.6
A vulnerability in Versa Director’s REST APIs allows attackers to exploit exposed authentication tokens via a GET request when the system is directly connected to the Internet, without revealing usernames or passwords. Versa recommends upgrading to patched versions or using a Web Application Firewall/API Gateway to block access to vulnerable URLs

As APIs evolve, so do the threats targeting them:

• The rise of AI-driven attacks capable of bypassing traditional security measures.
• Increased exploitation of business logic vulnerabilities.
• Growing importance of securing machine-to-machine communication.

Organizations must stay ahead by adopting advanced security frameworks like Mutual TLS and leveraging AI-powered threat detection tools.

How to Stop API Attacks

• Use OAuth 2.0 and OpenID Connect.
• Apply least privilege access.
• Enforce Multi-Factor Authentication (MFA).

• Set per-IP, per-user, and per-endpoint rate limits.
• Use token bucket or leaky bucket algorithms.

• Sanitize all inputs.
• Encode output to prevent injection attacks.

• Use tools like JSON Schema to validate request payloads.

• Regularly scan APIs with tools like Nuclei, OWASP ZAP, and Burp Suite.
• Employ fuzz testing and dynamic analysis.

• Use API gateways to enforce policies.
• Employ Web Application Firewalls for anomaly detection.

• Restrict to only what’s needed (e.g., GET, POST).

• Centralized logging with tools like ELK Stack or Splunk.
• Set alerts on anomalous behaviors.

• Return only necessary fields.
• Apply field-level encryption where necessary.

10. Use of Secure Headers

• Enforce HTTPS.
• Apply security headers like Content-Security-Policy, Strict-Transport-Security, etc.

OWASP API Security Top 10

Familiarize your team with OWASP’s API Security Top 10. 

These are:

1. BOLA
2. Broken Authentication
3. Excessive Data Exposure
4. Lack of Resources & Rate Limiting
5. Broken Function Level Authorization
6. Mass Assignment
7. Security Misconfiguration
8. Injection
9. Improper Asset Management
10. Insufficient Logging & Monitoring

Conclusion

API security is no longer optional. With APIs handling critical business data and services, their protection must be a top priority. By understanding how attackers exploit APIs and implementing layered security controls, organizations can significantly reduce their attack surface.

Take proactive steps—assess your API inventory, secure your authentication flows, implement robust logging, and continuously test for vulnerabilities. With the right strategy in place, you can turn your APIs from a liability into a stronghold of digital resilience.

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