CVE-2026-75509

Description

joserfc is a Python library that provides an implementation of several JSON Object Signing and Encryption (JOSE) standards. Prior to version 1.7.3, JWTClaimsRegistry applies membership matching to list-valued iss and sub claims, allowing an array-valued iss that contains the expected issuer to pass an intended equality check and enabling issuer-validation bypass. This issue is fixed in version 1.7.3.

CVSS Vector

References

• https://github.com/authlib/joserfc/commit/76ee6a59bf5773c0af00b99076c5e199031f97f1
• https://github.com/authlib/joserfc/security/advisories/GHSA-r74j-q665-7rpj