Advisories for Pypi/Joserfc package

joserfc.jwt.decode accepts attacker-forged HMAC-signed tokens when the caller-supplied verification key is the empty string or None. HMACAlgorithm.sign and HMACAlgorithm.verify in src/joserfc/_rfc7518/jws_algs.py:62-70 feed whatever OctKey.get_op_key(…) produced into hmac.new(…), and OctKey.import_key only emits a SecurityWarning when the raw key is shorter than 14 bytes without rejecting zero-length input. Any application whose JWT secret is sourced from an unset environment variable, an unset Redis / DB row, a key finder fallback that returns …

Testing revealed that joserfc accepts oversized RFC7797 b64=false JWS payloads without applying JWSRegistry.max_payload_length. The normal JWS compact and flattened JSON paths reject payloads above the configured payload-size limit with ExceededSizeError. The RFC7797 unencoded payload paths do not make the same check. A valid b64=false compact or flattened JSON JWS can therefore deserialize successfully with a payload larger than JWSRegistry.max_payload_length. This creates a moderate availability/resource-exhaustion risk for applications that accept lower-trust …

A resource exhaustion vulnerability in joserfc allows an unauthenticated attacker to cause a Denial of Service (DoS) via CPU exhaustion. When the library decrypts a JSON Web Encryption (JWE) token using Password-Based Encryption (PBES2) algorithms, it reads the p2c (PBES2 Count) parameter directly from the token's protected header. This parameter defines the number of iterations for the PBKDF2 key derivation function. Because joserfc does not validate or bound this value, …

The ExceededSizeError exception messages are embedded with non-decoded JWT token parts and may cause Python logging to record an arbitrarily large, forged JWT payload.