CVE-2026-120459

python-jose through 3.5.0 Authentication Bypass via Empty HMAC Key

Published Nov 2, 2026 CVSS 4.0 · 9.1 Critical EPSS < 1% KEV · Not listed
Description
python-jose through 3.5.0 contains an authentication bypass vulnerability that allows unauthenticated attackers to forge JWTs because HMACKey and CryptographyHMACKey accept zero-length HMAC secrets. When an application's HS256/HS384/HS512 verification key resolves to empty, such as an oct JWK with empty k, attackers can forge tokens with arbitrary claims that jwt.decode accepts.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

No advisories available
History
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'total'}, 'version': '2.0.3'}

Type Values Removed Values Added
Description python-jose through 3.5.0 contains an authentication bypass vulnerability that allows unauthenticated attackers to forge JWTs because HMACKey and CryptographyHMACKey accept zero-length HMAC secrets. When an application's HS256/HS384/HS512 verification key resolves to empty, such as an oct JWK with empty k, attackers can forge tokens with arbitrary claims that jwt.decode accepts.
Title python-jose through 3.5.0 Authentication Bypass via Empty HMAC Key
First Time appeared Python-jose Project
Python-jose Project python-jose
Weaknesses CWE-347
CPEs cpe:2.3:a:python-jose_project:python-jose:*:*:*:*:*:*:*:*
Vendors & Products Python-jose Project
Python-jose Project python-jose
References
Metrics cvssV3_1

{'score': 7.4, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N'}

cvssV4_0

{'score': 9.1, 'vector': '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'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
VulnCheck
Published
Updated
Nov 9, 2026, 2:01 PM
Reserved
Nov 2, 2026, 12:42 PM
Status
Awaiting Analysis
Published
Nov 2, 2026, 3:17 PM
Modified
Nov 9, 2026, 2:17 PM