Understanding CSRF Protection and JWT Authentication in Spring Security

Cross-Site Request Forgery (CSRF) and JSON Web Tokens (JWT) are two fundamental concepts in securing web applications. While Spring Security handles both effectively, certain default behaviors — such as bypassing CSRF protection for JWT-authenticated requests — might not align with specific application requirements. Let’s dive into why Spring Security skips CSRF for JWT and how you can customize this behavior to suit your needs.

What Is CSRF?

CSRF is an attack where a malicious website tricks a user’s browser into making unauthorized requests to a target application where the user is authenticated. It exploits the fact that browsers automatically send cookies with requests, allowing attackers to perform actions on behalf of users without their consent.

To mitigate CSRF, web applications often rely on CSRF tokens. These tokens are unique to each user session and must be included in state-modifying requests (e.g., POST, PUT, DELETE).

JWT Authentication and Statelessness

JWTs are commonly used for stateless authentication in REST APIs. A JWT is typically sent in the Authorization: Bearer header of HTTP requests. Because JWTs don’t rely on cookies or server-side sessions, they inherently…