Live › vulnerability › CVE-2026-120459
python-jose accepts zero-length HMAC secrets, so when an HS256, HS384 or HS512 verification key resolves to empty, an attacker can sign tokens with arbitrary claims. The forged tokens pass jwt.decode, which means an attacker can log in as any user the application trusts.
Summary written from the sources below. Check the originals before acting.
First seen by InfraStack 2026-11-02 15:24 UTC. All times on this page are UTC.
Applications that use python-jose to verify HS256, HS384 or HS512 tokens are exposed when the verification key can resolve to an empty value, for example an oct JWK with an empty k. Applications that use asymmetric algorithms or always supply a non-empty secret are not described as affected. The sources do not say whether a default configuration produces an empty key.
No product ranges from the sources yet.
python-jose in the lockfile or pip show python-jose to find the installed version.jwt.decode calls that use HS256, HS384 or HS512, and check where the key comes from.k value.3.5.0Each row is the first time that source carried this signal. The analyst’s rows are its own findings.
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.
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