Description

The scanner detected that the application supports the 'x5c' parameter in the header of a JSON Web Token (JWT). This parameter specifies the X.509 certificate chain used to verify the token's signature. Without proper validation of the certificate chain, an attacker may supply a malicious certificate, potentially enabling the creation of forged JWTs with arbitrary payloads. Attackers might be able to tamper with the values inside the JWT token payload and escalate privileges, impersonate users or trigger unintended application states that were meant to be prevented by the use of a tamper-proof token solution.

Remediation

To fix this vulnerability, you should either disable support for the 'x5c' header parameter or implement proper validation of the X.509 certificate chain specified in it. The server-side code responsible for checking the JWT token should be audited and fixed in order to allow for the proper verification of the provided signature.

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