CVE-2026-120459
High
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.
SeverityHigh
CVSS7.4
Exploit probability—
ProductMpdavis Python-jose
PublishedNov 2, 2026
First seenNov 4, 2026
Weakness typeCWE-347CWE-347
How to fix
Sources list no fixed version or patch link for this vulnerability.
Affected products
| Product | Affected versions | Fixed in |
|---|---|---|
| mpdavis python-jose | v ≤ 3.5.0 | — |
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