API Security in 2026: The Mistakes Exposing Companies Without Them Noticing

Why Are APIs Being Attacked More and More?

Unlike traditional applications, APIs typically process directly:

• Financial data
• Personal information
• Authentication
• Banking integrations
• Internal business data
• Administrative resources

On top of that, modern APIs often have hundreds of endpoints, significantly increasing the attack surface.

The Most Common Problems Found in APIs

1. Broken Access Control

This remains the most critical flaw in modern APIs.

Common example

GET /api/orders/10452
Authorization: Bearer eyJhbGciOi...
    

If the API doesn't validate ownership of the resource, simply changing the ID is enough to access other users' orders.

Impact

• Data leakage
• Cross-tenant exposure
• Financial fraud
• LGPD violation

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2. Insecure JWTs

Poorly implemented JWTs remain extremely common.

// Vulnerable

jwt.sign(payload, "123456", {
    expiresIn: '365d'
});
    

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3. APIs Without Rate Limiting

The absence of rate limiting enables automated attacks, brute force, and user enumeration.

POST /api/login
POST /api/login
POST /api/login
    

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4. Excessive Data Exposure

Many APIs return more data than they really should.

{
    "id": 1042,
    "name": "John Doe",
    "email": "[email protected]",
    "internalRole": "admin"
}
    

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5. Insecure GraphQL

Misconfigured GraphQL APIs can expose entire schemas, allow excessive queries, and leak sensitive information.

What We Usually Find in API Pentests

• Excessive trust in the frontend
• Partially implemented authorization
• Publicly exposed Swagger
• Insecure versioning
• Forgotten administrative endpoints

How Companies Can Reduce the Risks

1. Validate authorization on the backend

The frontend should never be responsible for validating permissions.

2. Implement MFA

3. Implement Rate Limiting

4. Monitor API logs

5. Run Recurring Pentests

Tools Used in API Pentests

• Burp Suite Professional
• OWASP ZAP
• Postman
• Caido
• ffuf
• nuclei
• httpx

Basic API Security Checklist

Conclusion

APIs have become one of the main attack vectors in modern applications.

In many recent incidents, the problem wasn't related to extremely sophisticated vulnerabilities, but rather to simple authorization flaws, excessive data exposure, and insecure configurations.

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