CVE-2026-102272

HIGH 7.4

PyJWT BOM Bypass

CVSS Score

7.4

EPSS Score

0.0%

EPSS Percentile

0th

PyJWT is a Python implementation of JSON Web Token standards. From 2.13.0 until 2.14.0, HMACAlgorithm.prepare_key in jwt/algorithms.py is affected because raw-JWK detector does not normalize accepted Unicode byte-order marks before checking for JSON. This occurs when a public JWK is prefixed with a UTF-8 BOM and used in a mixed-algorithm verification path. As a result, public JWK bypasses asymmetric-key detection and becomes the HMAC secret. Consequently, an attacker who knows the public key can forge authenticated tokens. This issue is fixed in version 2.14.0.

CWE	CWE-347
Vendor	jpadilla
Product	pyjwt
Published	Sep 28, 2026

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CVSS v3 Breakdown

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N

Attack Vector

Network

Attack Complexity

High

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

None

Affected Versions

jpadilla / pyjwt

>= 2.13.0, < 2.14.0

References

NVD ↗ CVE.org ↗ EPSS Data ↗

github.com: https://github.com/jpadilla/pyjwt/security/advisories/GHSA-r6x4-923q-g947 github.com: https://github.com/jpadilla/pyjwt/commit/180783930de91876bc0d601f826a1f2956057291 github.com: https://github.com/jpadilla/pyjwt/releases/tag/2.14.0