Instituto Nacional de ciberseguridad. Sección Incibe
Instituto Nacional de Ciberseguridad. Sección INCIBE-CERT

CVE-2026-28498

Gravedad CVSS v4.0:
ALTA
Tipo:
No Disponible / Otro tipo
Fecha de publicación:
16/03/2026
Última modificación:
17/03/2026

Descripción

*** Pendiente de traducción *** 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.

Productos y versiones vulnerables

CPE Desde Hasta
cpe:2.3:a:authlib:authlib:*:*:*:*:*:*:*:* 1.6.9 (excluyendo)