CVE-2026-28498

Fixed in a distro release EPSS <1%CVSS 8.2

Authlib is a Python library which builds OAuth and OpenID Connect servers. Prior to version 1.6.9, a library-level vulnerability was identified in the Authlib Python library concerning the validation of OpenID Connect (OIDC) ID Tokens. Specifically, the internal hash verification logic (_verify_hash) responsible for validating the at_hash (Access Token Hash) and c_hash (Authorization Code Hash) claims exhibits a fail-open behavior when encountering an unsupported or unknown cryptographic algorithm. This flaw allows an attacker to bypass mandatory integrity protections by supplying a forged ID Token with a deliberately unrecognized alg header parameter. The library intercepts the unsupported state and silently returns True (validation passed), inherently violating fundamental cryptographic design principles and direct OIDC specifications. This issue has been patched in version 1.6.9.

Published 2026-03-16 · CVE record · OSV

Products: authlib, Red Hat Ansible Automation Platform 2.6, Red Hat Quay 3.10, Red Hat Quay 3.12, Red Hat Quay 3.15, Red Hat Quay 3.16, Red Hat Lightspeed Core, Red Hat Ansible Automation Platform 2, Red Hat OpenShift AI (RHOAI), Red Hat Satellite 6

Fixed upstream

Distro releases