PyJWT: PyJWK accepts empty HMAC keys, bypassing PyJWT's empty-key validation

SummaryA service that verifies HS256 tokens using an empty oct JWK through PyJWK, including a PyJWK obtained from PyJWKSet, can therefore accept attacker-generated tokens as authenticated.PyJWT 2.13.0 rejects an empty HMAC key when it is supplied through the raw str/bytes key path, but accepts th...

PYSEC-2026-4143 PyJWT: PyJWK accepts empty HMAC keys, bypassing PyJWT's empty-key validation

Summary A service that verifies HS256 tokens using an empty oct JWK through PyJWK, including a PyJWK obtained from PyJWKSet, can therefore accept attacker-generated tokens as authenticated. PyJWT 2.13.0 rejects an empty HMAC key when it is supplied through the raw str/bytes key path, but accepts...

PyJWT: PyJWK accepts empty HMAC keys, bypassing PyJWT's empty-key validation

Summary A service that verifies HS256 tokens using an empty oct JWK through PyJWK, including a PyJWK obtained from PyJWKSet, can therefore accept attacker-generated tokens as authenticated. PyJWT 2.13.0 rejects an empty HMAC key when it is supplied through the raw str/bytes key path, but accepts...

GHSA-9J54-FG26-WV3R PyJWT: PyJWK accepts empty HMAC keys, bypassing PyJWT's empty-key validation

Summary A service that verifies HS256 tokens using an empty oct JWK through PyJWK, including a PyJWK obtained from PyJWKSet, can therefore accept attacker-generated tokens as authenticated. PyJWT 2.13.0 rejects an empty HMAC key when it is supplied through the raw str/bytes key path, but accepts...

Improper Handling of Exceptional Conditions

Overview PyJWT is a Python implementation of RFC 7519. Affected versions of this package are vulnerable to Improper Handling of Exceptional Conditions via the PyJWK constructor in jwt/apijwk.py when processing a JWK set containing a malformed key. An attacker who can supply a JWK set with a...

Improper Verification of Cryptographic Signature

Overview PyJWT is a Python implementation of RFC 7519. Affected versions of this package are vulnerable to Improper Verification of Cryptographic Signature via the verifysignature method in jwt/apijws.py when a PyJWK object is used to verify an HMAC-signed token. In the vulnerable code path,...

CVE-2026-102266 PyJWK accepts empty HMAC keys, bypassing PyJWT's empty-key validation

PyJWT is a Python implementation of JSON Web Token standards. From 2.13.0 until 2.14.0, HMACAlgorithm.fromjwk is affected because PyJWK verification path used the decoded key without applying preparekey validation. This occurs when a trusted JWK Set contains an oct entry with an empty k value. As...

CVE-2026-102266 PyJWK accepts empty HMAC keys, bypassing PyJWT's empty-key validation

PyJWT is a Python implementation of JSON Web Token standards. From 2.13.0 until 2.14.0, HMACAlgorithm.fromjwk is affected because PyJWK verification path used the decoded key without applying preparekey validation. This occurs when a trusted JWK Set contains an oct entry with an empty k value. As...

CVE-2026-102266 PyJWK accepts empty HMAC keys, bypassing PyJWT's empty-key validation

PyJWT is a Python implementation of JSON Web Token standards. From 2.13.0 until 2.14.0, HMACAlgorithm.fromjwk is affected because PyJWK verification path used the decoded key without applying preparekey validation. This occurs when a trusted JWK Set contains an oct entry with an empty k value. As...

GHSA-JQ35-7PRP-9V3F PyJWT: Algorithm allow-list bypass when decoding with `PyJWK` / `PyJWKClient` keys

!NOTE Scored assuming a deployment where algorithm policy functions as an authentication/authorization boundary. In deployments where the algorithm policy enforces crypto agility only, the practical confidentiality impact is lower and the issue is closer to an integrity-of-policy-enforcement bug...

PyJWT: Algorithm allow-list bypass when decoding with `PyJWK` / `PyJWKClient` keys

!NOTE Scored assuming a deployment where algorithm policy functions as an authentication/authorization boundary. In deployments where the algorithm policy enforces crypto agility only, the practical confidentiality impact is lower and the issue is closer to an integrity-of-policy-enforcement bug...

Linux Distros Unpatched Vulnerability : CVE-2026-48523

The Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied patch available. - PyJWT is a JSON Web Token implementation in Python. From 2.9.0 to 2.12.1, there is a verifier-side algorithm allow-list bypass when jwt.decode or...

Improper Verification of Cryptographic Signature

Overview Affected versions of this package are vulnerable to Improper Verification of Cryptographic Signature via the jwt.decode or jwt.decodecomplete functions when used with a PyJWK key. An attacker can bypass algorithm restrictions and gain unauthorized access to protected resources by signing...

CVE-2026-48523

PyJWT is a JSON Web Token implementation in Python. From 2.9.0 to 2.12.1, there is a verifier-side algorithm allow-list bypass when jwt.decode or jwt.decodecomplete are called with a PyJWK key. The token header alg is checked against the caller-supplied algorithms allow-list, but signature...

PYSEC-2026-176

PyJWT is a JSON Web Token implementation in Python. From 2.9.0 to 2.12.1, there is a verifier-side algorithm allow-list bypass when jwt.decode or jwt.decodecomplete are called with a PyJWK key. The token header alg is checked against the caller-supplied algorithms allow-list, but signature...

UBUNTU-CVE-2026-48523

PyJWT is a JSON Web Token implementation in Python. From 2.9.0 to 2.12.1, there is a verifier-side algorithm allow-list bypass when jwt.decode or jwt.decodecomplete are called with a PyJWK key. The token header alg is checked against the caller-supplied algorithms allow-list, but signature...

CVE-2026-48523 PyJWT: Algorithm allow-list bypass when decoding with `PyJWK` / `PyJWKClient` keys

PyJWT is a JSON Web Token implementation in Python. From 2.9.0 to 2.12.1, there is a verifier-side algorithm allow-list bypass when jwt.decode or jwt.decodecomplete are called with a PyJWK key. The token header alg is checked against the caller-supplied algorithms allow-list, but signature...

CVE-2026-48523

PyJWT vulnerability affecting versions 2.9.0–2.12.1 where verifier-side algorithm allow-list bypass occurs when decoding with a PyJWK/PyJWKClient key. The token header’s alg is checked against the caller-supplied allow-list, but the signature is verified using the algorithm bound to the PyJWK obj...

CVE-2026-48523 PyJWT: Algorithm allow-list bypass when decoding with `PyJWK` / `PyJWKClient` keys

PyJWT is a JSON Web Token implementation in Python. From 2.9.0 to 2.12.1, there is a verifier-side algorithm allow-list bypass when jwt.decode or jwt.decodecomplete are called with a PyJWK key. The token header alg is checked against the caller-supplied algorithms allow-list, but signature...

CVE-2026-48523: Improper Verification of Cryptographic Signature

PyJWT is a JSON Web Token implementation in Python. From 2.9.0 to 2.12.1, there is a verifier-side algorithm allow-list bypass when jwt.decode or jwt.decodecomplete are called with a PyJWK key. The token header alg is checked against the caller-supplied algorithms allow-list, but signature...