Top 10 REST API Security Mistakes and How to Fix Them

REST APIs are the foundation of modern web and mobile applications. However, poor API security can expose sensitive data, making your application vulnerable to attacks like data breaches, unauthorized access, and injection attacks.

In this article, we’ll cover 10 common REST API security mistakes and how to fix them with best practices. To demonstrate each mistake, we will use Java and Spring Boot examples.

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1️⃣ Exposing Sensitive Data in API Responses 🔓

❌ Mistake: Returning Passwords, API Keys, or Internal Data

Some developers accidentally expose sensitive information in API responses.

Bad Example: ❌

{
    "id": 1,
    "email": "user@example.com",
    "password": "mypassword123",
    "apiKey": "XYZ-SECRET-123"
}

✔ Risk:

• Hackers can steal credentials and gain unauthorized access.
• Exposed API keys can compromise your entire system.

✅ Solution: Use DTOs and Restrict Fields