Incorrect Behavior Order: Validate Before Canonicalize in pyjwt - CVE-2026-102269

Vulnerability identifier: #VU150520

CSH Severity: Medium

CVSS v4: 6.3 [CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N]

CVE-ID: CVE-2026-102269

CWE-ID: CWE-180

Exploitation vector: Remote access

Exploit availability: No public exploit available

The vulnerability allows a remote attacker to bypass token revocation controls.

The vulnerability exists due to incorrect behavior order: validate before canonicalize in compact JWS signature-segment decoding when processing a compact JWS with a non-canonical signature segment. A remote attacker can append non-Base64URL characters to a valid token's signature segment to bypass token revocation controls.

Exploitation requires an application to use the raw serialized token as the identity for revocation, replay, rate-limit, or cache state.

pyjwt
SUSE Linux Enterprise Server 15 SP6
SUSE Linux Enterprise Server 15 SP5
SUSE Linux Enterprise Server 15 SP4
SUSE Linux Enterprise High Performance Computing ESPOS 15
SUSE Linux Enterprise Server 15
SUSE Linux Enterprise High Performance Computing LTSS 15
SUSE Linux Enterprise High Performance Computing 15
SUSE Linux Enterprise Server for SAP Applications 15
SUSE Linux Enterprise Desktop 15
SUSE Manager Server
SUSE Manager Proxy
SUSE Manager Retail Branch Server
Public Cloud Module
Python 3 Module
openSUSE Leap
openEuler
python-jwt
python-jwt-help
python3-jwt
python311-PyJWT

Install security update from vendor's website.

pyjwt - update to 2.14.0
python-jwt - addressed in versions 2.3.0-12, 2.8.0-11
python-jwt-help - addressed in versions 2.3.0-12, 2.8.0-11
python3-jwt - addressed in versions 2.3.0-12, 2.8.0-11
python311-PyJWT - update to 2.8.0-150400.8.20.1

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

• Multiple vulnerabilities in pyjwt
• openEuler 22.03 LTS SP4 update for python-jwt
• openEuler 24.03 LTS SP3 update for python-jwt
• openEuler 24.03 LTS SP1 update for python-jwt
• openEuler 24.03 LTS SP4 update for python-jwt
• SUSE update for python-PyJWT