CVEvulnerability

CVE-2026-102271

7.4 HIGH Published 2026-09-28 Modified 2026-10-06 Official page ↗
Status
Analyzed
Published
2026-09-28
Last modified
2026-10-06
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
Weaknesses
CWE-347

Description

PyJWT is a Python implementation of JSON Web Token standards. From 2.4.0 until 2.14.0, PyJWT HMACAlgorithm.prepare_key is affected because asymmetric-key guard relies on textual markers that are absent from DER encoding. This occurs when an application mixes HMAC and asymmetric algorithms and supplies a DER public key as the shared verification key. As a result, PyJWT uses public DER bytes as an HMAC secret. Consequently, an attacker who knows the public key can forge authenticated HMAC tokens. This issue is fixed in version 2.14.0.

Affected configurations

• pyjwt project pyjwt (>= 2.4.0 < 2.14.0)

Related

Weakness · CWE (1)

  • CWE-347 Improper Verification of Cryptographic Signature weakness

References