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CVE-2026-27962

CRITICAL(9.1)

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

Risk Signal Score23/100 — NIEDRIG
  • CVSS 9.1 — Kritisch

EPSS-Score

1%

Exploit-Wahrscheinlichkeit (30 Tage)

CVSS Score

9.1

Technische Schwere

Beschreibung

Authlib is a Python library which builds OAuth and OpenID Connect servers. Prior to version 1.6.9, a JWK Header Injection vulnerability in authlib's JWS implementation allows an unauthenticated attacker to forge arbitrary JWT tokens that pass signature verification. When key=None is passed to any JWS deserialization function, the library extracts and uses the cryptographic key embedded in the attacker-controlled JWT jwk header field. An attacker can sign a token with their own private key, embed the matching public key in the header, and have the server accept the forged token as cryptographically valid — bypassing authentication and authorization entirely. This issue has been patched in version 1.6.9.

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