Name: CVE-2026-102271: Improper Verification of Cryptographic Signature
Creator: Rapid7
Published: 2026-09-28T00:00:00.000Z
License: https://www.rapid7.com/legal/website-terms-of-use/
Keywords: CVE, CVE-2026-102271, CWE-347, CVSS 7.4, EPSS 0.0018

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.

CVSS Details

CVSS 3.1 Base Score: 7.4
CVSS 3.1 Vector: (CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N)

Covered by Rapid7

Product	Vendor Advisory	Solution File	Added	Published
Redhat_linux	—	No solution exists	Oct 13, 2026	Sep 28, 2026
Ubuntu	—	Upgrade python3-jwt (Ubuntu Pro)Upgrade python3-jwtUpgrade python-jwt (Ubuntu Pro)	Oct 14, 2026	Oct 13, 2026

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CVSS Details

Covered by Rapid7

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