Vulnerability in authlib joserfc

[ Why it matters ]Priority signals

• Public proof-of-concept exploit exists (CISA SSVC)
• Critical severity: CVSS 9.1

[ Description ]Official description

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.

[ Fixes ]Fixes and patches

No fix or interim patch is linked from our sources yet. Check the vendor references below and limit exposure of affected systems until a fix is available.

[ References ]References

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