CVEvulnerability

CVE-2026-102266

9.1 CRITICAL Published 2026-09-28 Modified 2026-10-07 Official page ↗
Status
Analyzed
Published
2026-09-28
Last modified
2026-10-07
Assigner
[email protected]
CVSS 3.1 ([email protected])
7.4 HIGH — CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N
CVSS 3.1 ([email protected])
9.1 CRITICAL — CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
Weaknesses
CWE-347

Description

PyJWT is a Python implementation of JSON Web Token standards. From 2.13.0 until 2.14.0, HMACAlgorithm.from_jwk is affected because PyJWK verification path used the decoded key without applying prepare_key validation. This occurs when a trusted JWK Set contains an oct entry with an empty k value. As a result, an attacker signs an HMAC token with the same zero-length key accepted by PyJWT. Consequently, forged token can carry arbitrary authenticated claims. This issue is fixed in version 2.14.0.

Affected configurations

• pyjwt project pyjwt 2.13.0

Related

Weakness · CWE (1)

  • CWE-347 Improper Verification of Cryptographic Signature weakness

References