CVE-2026-102269

MEDIUM 4.8

PyJWT: Non-canonical signature segments enable raw-token revocation bypass

CVSS Score

4.8

EPSS Score

0.0%

EPSS Percentile

0th

PyJWT is a Python implementation of JSON Web Token standards. Prior to 2.14.0, PyJWT signature segment is affected because signature segment decoding accepts characters outside the canonical Base64URL representation. This occurs when non-Base64URL characters are appended to a valid compact JWS signature segment. As a result, base64url_decode produces the same signature bytes for different serialized segments. Consequently, raw-token revocation checks can fail to recognize an equivalent modified token. This issue is fixed in version 2.14.0.

CWE	CWE-180
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:L/I:L/A:N

Attack Vector

Network

Attack Complexity

High

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

Low

Integrity

Low

Availability

None

Affected Versions

jpadilla / pyjwt

< 2.14.0

References

NVD ↗ CVE.org ↗ EPSS Data ↗

github.com: https://github.com/jpadilla/pyjwt/security/advisories/GHSA-hxm8-2xgr-2p9m github.com: https://github.com/jpadilla/pyjwt/commit/e6f48401001609a8f99e71fcaf355fb895d508a8 github.com: https://github.com/jpadilla/pyjwt/releases/tag/2.14.0