CVE-2026-120459

high

python-jose through 3.5.0 contains an authentication bypass vulnerability that allows unauthenticated attackers to forge JWTs because HMACKey and CryptographyH…

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

7.4

7.4 (CVSS v3.1)

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N

Severity source: NVD CVSS v3.1 (disclosure@vulncheck.com)

Timeline (UTC)

Published: 2026-11-02 15:17

Modified: 2026-11-02 19:14

NVD status: Awaiting Analysis

Last synced 1 day ago

Verified against the source API 2026-11-03 07:35 UTC

Exploitation

Not listed in CISA KEV (as of last catalog sync)

Absence from KEV does not mean a CVE is not exploited. Exploitation status: unknown (no authoritative evidence in our sources).

Affected products

Not reported by the source (unknown — not "none").

Weakness classification (CWE)

CWE-347

Source: NVD / CISA. “NVD-CWE-Other” and “NVD-CWE-noinfo” mean NVD could not assign a specific weakness.

Mitigation & advisories

No vendor advisory or patch reference tagged by NVD. Check the references below.

References

https://github.com/mpdavis/python-jose/blob/3.5.0/jose/backends/cryptography_backend.py disclosure@vulncheck.com
https://github.com/mpdavis/python-jose/blob/3.5.0/jose/backends/native.py disclosure@vulncheck.com
https://github.com/mpdavis/python-jose/issues/398 disclosure@vulncheck.com
https://www.vulncheck.com/advisories/python-jose-through-3.5.0-authentication-bypass-via-e... disclosure@vulncheck.com

Data sources

NVD CVE API 2.0 — fetched 2026-11-03 07:35 UTC · record ↗

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