Improper Verification of Cryptographic Signature in pyjwt - CVE-2026-48526

Vulnerability identifier: #VU132105

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-2026-48526

CWE-ID: CWE-347

Exploitation vector: Remote access

Exploit availability: No public exploit available

The vulnerability allows a remote attacker to forge JWT tokens and impersonate users.

The vulnerability exists due to improper verification of cryptographic signature in the JWT verification logic when decoding JSON Web Tokens with both symmetric and asymmetric algorithms enabled and a raw JSON Web Key supplied as the key. A remote attacker can supply a token that specifies HS256 and sign it using the issuer public JWK as the HMAC secret to forge JWT tokens and impersonate users.

Exploitation requires the verifier to allow HS* and an asymmetric algorithm in the same call and to pass a public-key value as the key.

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 LTSS 15
SUSE Linux Enterprise High Performance Computing 15
SUSE Linux Enterprise Server for SAP Applications 15
SUSE Linux Enterprise High Performance Computing ESPOS 15
SUSE Linux Enterprise Server 15
SUSE Linux Enterprise Desktop 15
SUSE Linux Enterprise Real Time 15
SUSE Manager Retail Branch Server
SUSE Manager Server
SUSE Manager Proxy
SUSE Linux Enterprise Micro
SUSE Linux Micro
Public Cloud Module
Basesystem Module
Python 3 Module
openSUSE Leap
python3-PyJWT
python311-PyJWT

Install security update from vendor's website.

pyjwt - update to 2.13.0
python3-PyJWT - update to 2.4.0-150200.3.14.1
python311-PyJWT - addressed in versions 2.8.0-150400.8.13.1, 2.12.1-slfo.1.1_2.1

• https://github.com/jpadilla/pyjwt/security/advisories/GHSA-xgmm-8j9v-c9wx

• Multiple vulnerabilities in pyjwt
• SUSE update for python-PyJWT
• SUSE update for python-PyJWT
• SUSE update for python-PyJWT