CVE-2026-102946

joserfc is a Python library that provides an implementation of several JSON Object Signing and Encryption (JOSE) standards. Prior to 1.7.4, joserfc.jws.deserialize_json() accepts a JWS General JSON Serialization with an empty signatures array as authenticated. The verify_general_json() loop performs no iterations for the empty array and returns success because no signature check failed, allowing an attacker without a signing key to supply an arbitrary payload that relying applications may treat as authentic. The issue affects the General JSON Serialization path; compact JWS and JWT decoding, Flattened JSON serialization, and JWE JSON processing do not follow this vulnerable path. This issue is fixed in version 1.7.4.

• https://github.com/authlib/joserfc/commit/f409f8f058225d7686acab6546c94593e4c1bfbe
• https://github.com/authlib/joserfc/releases/tag/1.7.4
• https://github.com/authlib/joserfc/security/advisories/GHSA-4pp3-559j-c5c2
• https://github.com/authlib/joserfc/security/advisories/GHSA-4pp3-559j-c5c2