1. Web Security Academy
  2. JWT attacks
  3. Lab

Lab: JWT authentication bypass via jku header injection


This lab uses a JWT-based mechanism for handling sessions. The server supports the jku parameter in the JWT header. However, it fails to check whether the provided URL belongs to a trusted domain before fetching the key.

To solve the lab, forge a JWT that gives you access to the admin panel at /admin, then delete the user carlos.

You can log in to your own account using the following credentials: wiener:peter


We recommend familiarizing yourself with how to work with JWTs in Burp Suite before attempting this lab.

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