PyJWT is a JSON Web Token implementation in Python. Prior to 2.13.0, when the verifier is decoding JSON Web Tokens, while supporting both asymmetric and HMAC al…

PyJWT, a JSON Web Token implementation in Python, contains a vulnerability prior to version 2.13.0 where the library fails to validate the use of JSON Web Keys in HMAC algorithms. This flaw allows attackers to use the issuer's public key as the secret key for HMAC algorithm verification when the verifier supports both asymmetric and HMAC algorithms. The vulnerability enables potential token forgery attacks and has been fixed in version 2.13.0.