Introduction:
Web apps power our digital lives, but they also create massive attack surfaces. At TrustStack Security, we’re constantly testing apps and uncovering vulnerabilities, many of which are repeat offenders. In this blog, we highlight the top 5 web application vulnerabilities of 2025 and show you how to mitigate them.
1. Broken Access Control
What it is: Unauthorized users accessing restricted resources.
Example: An attacker changes a user ID in a URL and accesses another user’s data.
Fix: Enforce strict backend authorization. Don’t rely on client-side controls.
2. Server-Side Request Forgery (SSRF)
What it is: Exploiting the server to send requests internally.
Example: An attacker forces your server to access internal resources or metadata services (e.g., AWS EC2).
Fix: Sanitize user input and restrict outbound connections.
3. Insecure Deserialization
What it is: Attackers manipulate serialized objects to gain code execution.
Example: A tampered cookie leads to remote code execution via deserialization.
Fix: Avoid native deserialization where possible. Use integrity checks.
4. DOM-based XSS
What it is: Client-side JavaScript is manipulated to inject scripts.
Example: An attacker inserts a payload into the URL hash, which the JS app renders.
Fix: Use safe DOM manipulation methods and sanitize all inputs.
5. API Misconfigurations
What it is: Overly permissive endpoints, missing auth, or excessive data exposure.
Example: A public API leaks user data that shouldn’t be visible.
Fix: Use proper rate limiting, input validation, and strong authentication.
Conclusion:
Security isn’t about eliminating bugs—it’s about staying ahead of the curve. These vulnerabilities are dangerous because they’re often missed. At TrustStack, our testing methodology uncovers these flaws before attackers do.
