Summary
Acunetix 360 detected a path traversal vulnerability in a JSON Web Token's kid header parameter. This allows for the forgery of valid JSON Web Tokens with arbitrary payloads.
Impact
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
In order to fix this vulnerability, the underlying path traversal vulnerability has to be fixed first. It is important that the kid parameter is free from any injection vulnerabilities and has a proper fallback on error conditions, such as invalid data which is returned from the respective storage solution of the secret key.