![Cracking JWTs: A Bug Bounty Hunting Guide [Part 4]](https://miro.medium.com/v2/resize:fit:1080/1*_ef8znaafSCX1OMxF9DPZw.png "Cracking JWTs: A Bug Bounty Hunting Guide [Part 4]")
This article discusses how an insecure JKU header can be exploited to bypass JWT authentication by hosting a malicious key set and forging tokens. It highlights the importance of validating the source of JWKs to prevent privilege escalation. #JWTBypass #JKU Header Injection
Keypoints
- JWTs are vulnerable when the server blindly trusts the jku parameter.
- An attacker can host their own JWK Set URL to forge tokens and impersonate users.
- The vulnerability allows privilege escalation, including admin access.
- Must validate the source domain of the jku header to prevent exploitation.
- Using strict JWT configurations and additional authentication layers enhances security.