Improper Verification of Cryptographic Signature in pyjwt - CVE-2026-102268

Vulnerability identifier: #VU150525

CSH Severity: High

CVSS v4: 9.3 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N]

CVE-ID: CVE-2026-102268

CWE-ID: CWE-347

Exploitation vector: Remote access

Exploit availability: No public exploit available

The vulnerability allows a remote attacker to forge arbitrary-claim tokens.

The vulnerability exists due to improper verification of cryptographic signatures in HMACAlgorithm.prepare_key and is_pem_format when processing a loader-accepted PEM public key that is not recognized as PEM under a mixed algorithm allow-list. A remote attacker can sign an HS256 token using the public key as an HMAC secret to forge arbitrary-claim tokens.

Exploitation requires knowledge of the public verification key, cryptography to be installed, and use of the raw PEM non-PyJWK verification path.

pyjwt
SUSE Linux Enterprise Server 15 SP4
SUSE Linux Enterprise Server 15 SP5
SUSE Linux Enterprise Server 15 SP6
SUSE Linux Enterprise High Performance Computing 15
SUSE Linux Enterprise Server 15
SUSE Linux Enterprise High Performance Computing ESPOS 15
SUSE Linux Enterprise High Performance Computing LTSS 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
Ubuntu
openEuler
python3-jwt (Ubuntu package)
python-jwt (Ubuntu package)
python-jwt
python-jwt-help
python3-jwt
python311-PyJWT

Install security update from vendor's website.

pyjwt - update to 2.14.0
python3-jwt (Ubuntu package) - addressed in versions 1.3.0-1ubuntu0.1+esm3, 1.5.3+ds1-1ubuntu0.1+esm3, 1.7.1-2ubuntu2.1+esm3, 2.3.0-1ubuntu0.5, 2.7.0-1ubuntu0.3, 2.10.1-4ubuntu1.2
python-jwt (Ubuntu package) - addressed in versions 1.3.0-1ubuntu0.1+esm3, 1.5.3+ds1-1ubuntu0.1+esm3
python-jwt - addressed in versions 2.3.0-8, 2.8.0-6
python-jwt-help - addressed in versions 2.3.0-8, 2.8.0-6
python3-jwt - addressed in versions 2.3.0-8, 2.8.0-6
python311-PyJWT - update to 2.8.0-150400.8.20.1

• https://github.com/jpadilla/pyjwt/security/advisories/GHSA-ffc3-869f-jxw9
• https://github.com/jpadilla/pyjwt/commit/8b4e233a22206b34ec1186e912e75c0b2396ac07

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