PyJWT is a Python implementation of JSON Web Token standards. From 2.13.0 until 2.14.0, PyJWT HMACAlgorithm.prepare_key is affected because HMAC key guard only recognizes top-level public JWK forms and misses container representations. This occurs when an application allows HMAC and asymmetric algorithms and passes a public JWK container as the raw key. As a result, public asymmetric key material is accepted as the HMAC secret. Consequently, an attacker who knows the public key can forge a token with arbitrary authenticated claims. This issue is fixed in version 2.14.0.

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Mon, 28 Sep 2026 21:00:00 +0000

Type Values Removed Values Added
Description PyJWT is a Python implementation of JSON Web Token standards. From 2.13.0 until 2.14.0, PyJWT HMACAlgorithm.prepare_key is affected because HMAC key guard only recognizes top-level public JWK forms and misses container representations. This occurs when an application allows HMAC and asymmetric algorithms and passes a public JWK container as the raw key. As a result, public asymmetric key material is accepted as the HMAC secret. Consequently, an attacker who knows the public key can forge a token with arbitrary authenticated claims. This issue is fixed in version 2.14.0.
Title PyJWT accepts public JWK containers as HMAC secrets
Weaknesses CWE-347
References
Metrics cvssV3_1

{'score': 7.4, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N'}


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cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-09-28T20:38:28.161Z

Reserved: 2026-09-28T20:11:16.658Z

Link: CVE-2026-102273

cve-icon Vulnrichment

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cve-icon NVD

Status : Received

Published: 2026-09-28T21:17:15.497

Modified: 2026-09-28T21:17:15.497

Link: CVE-2026-102273

cve-icon Redhat

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cve-icon OpenCVE Enrichment

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Weaknesses