Improper Verification of Cryptographic Signature in pyjwt - CVE-2026-102271

Vulnerability identifier: #VU150524

CSH Severity: Medium

CVSS v4: 9.1 [CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N]

CVE-ID: CVE-2026-102271

CWE-ID: CWE-347

Exploitation vector: Remote access

Exploit availability: No public exploit available

The vulnerability allows a remote attacker to forge authentication tokens with arbitrary claims.

The vulnerability exists due to improper verification of cryptographic signatures in HMACAlgorithm.prepare_key when verifying tokens with DER-form asymmetric public keys while HMAC and asymmetric algorithms are enabled. A remote attacker can submit a forged HMAC-signed token to forge authentication tokens with arbitrary claims.

The issue does not affect PyJWK or PyJWKClient verification paths.

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-p4g4-x82p-q773
• https://github.com/jpadilla/pyjwt/commit/2798504fa2663364573cf2d1043d8d7fef389499

• 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