CVE-2026-44699
Received
Received - Intake
BaseFortify
Publication date: 2026-05-15
Last updated on: 2026-05-15
Assigner: GitHub, Inc.
Description
Description
LibJWT is a C JSON Web Token Library. From 3.0.0 to 3.3.2, libjwt accepts an RSA JWK that does not contain an alg parameter as the verification key for an HS256/HS384/HS512 token. In the OpenSSL backend, this causes HMAC verification to run with a zero-length key, so an attacker can forge a valid JWT without knowing any secret or RSA private key. This is an algorithm-confusion authentication bypass. It affects applications that load RSA keys from JWKS where alg is omitted, which is valid JWK syntax and common in real deployments, and then choose the verification algorithm from the JWT header, for example in a kid lookup callback. This vulnerability is fixed in 3.3.3.
CVSS Scores
EPSS Scores
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Meta Information
Affected Vendors & Products
Currently, no data is known.
Helpful Resources
Exploitability
CWE
KEV
| CWE ID | Description |
|---|---|
| CWE-347 | The product does not verify, or incorrectly verifies, the cryptographic signature for data. |
| CWE-327 | The product uses a broken or risky cryptographic algorithm or protocol. |
Attack-Flow Graph
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