CVE-2026-120459

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.

CVSS v3 7.4 HIGH

7.4^/10

CVSS v3 : HIGH

Vector :

Exploitability : 2.2 / Impact : 5.2

Attack Vector NETWORK

Attack Complexity HIGH

Privileges Required NONE

User Interaction NONE

Confidentiality Impact HIGH

Integrity Impact HIGH

Availability Impact NONE

Scope UNCHANGED

References

Link	Resource
https://github.com/mpdavis/python-jose/blob/3.5.0/jose/backends/cryptography_backend.py
https://github.com/mpdavis/python-jose/blob/3.5.0/jose/backends/native.py
https://github.com/mpdavis/python-jose/issues/398
https://www.vulncheck.com/advisories/python-jose-through-3.5.0-authentication-bypass-via-empty-hmac-key

Configurations

No configuration.

History

02 Nov 2026, 15:17

Type	Values Removed	Values Added
New CVE

Information

Published : 2026-11-02 15:17

Updated : 2026-11-02 19:14

NVD link : CVE-2026-120459

Mitre link : CVE-2026-120459

CVE.ORG link : CVE-2026-120459

JSON object : View

Products Affected

No product.

CWE

CWE-347

Improper Verification of Cryptographic Signature

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