Improper Verification of Cryptographic Signature Affecting python3-jwt+crypto package, versions <0:2.4.0-1.amzn2023.0.6


Severity

Recommended
0.0
high
0
10

Based on Amazon Linux security rating.

Threat Intelligence

EPSS
0.22% (12th percentile)

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  • Snyk IDSNYK-AMZN2023-PYTHON3JWTCRYPTO-21702773
  • published25 Oct 2026
  • disclosed28 Sept 2026

Introduced: 28 Sep 2026

CVE-2026-102271  (opens in a new tab)
CWE-347  (opens in a new tab)

How to fix?

Upgrade Amazon-Linux:2023 python3-jwt+crypto to version 0:2.4.0-1.amzn2023.0.6 or higher.
This issue was patched in ALAS2023-2026-3298.

NVD Description

Note: Versions mentioned in the description apply only to the upstream python3-jwt+crypto package and not the python3-jwt+crypto package as distributed by Amazon-Linux. See How to fix? for Amazon-Linux:2023 relevant fixed versions and status.

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 Base Scores

version 3.1