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CVE-2025-59420

Estado: ModificadaAlta (7.5)—

Authlib is a Python library which builds OAuth and OpenID Connect servers. Prior to version 1.6.4, Authlib’s JWS verification accepts tokens that declare unknown critical header parameters (crit), violating RFC 7515 “must‑understand” semantics. An attacker can craft a signed token with a critical header (for example, bork or cnf) that strict verifiers reject but Authlib accepts. In mixed‑language fleets, this enables split‑brain verification and can lead to policy bypass, replay, or privilege escalation. This issue has been patched in version 1.6.4.

CVSS

Probabilidad de explotación (EPSS)

EPSS (Exploit Prediction Scoring System, de FIRST) estima la probabilidad de que una vulnerabilidad sea explotada en 30 días. Complementa a CVSS (impacto) y a CISA KEV (explotación confirmada).

🎯 Técnicas ATT&CK

Cómo se explota esta vulnerabilidad y qué consigue el atacante, en el lenguaje de MITRE ATT&CK.

Vulnerabilidad en validación de tokens JWT que permite bypass de políticas de autenticación (CWE-345, CWE-863). Acceso remoto sin autenticación (AV:N, PR:N, UI:N) permite manipular tokens con parámetros críticos desconocidos para eludir verificadores estrictos, escalando privilegios o asumiendo iden

Inferido por nuestro agente de análisis a partir de la descripción oficial, el vector CVSS y la CWE, y comprobado por un supervisor. Puede contener errores.

🛡️ Mitigaciones ATT&CK que cubren estas técnicas

Privileged Account ManagementUser Account ManagementPassword PoliciesMulti-factor AuthenticationApplication Developer GuidanceActive Directory Configuration

Tecnologías afectadas (1)

Authlib — Authlib

CWE

Referencias

JSON original (NVD)

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