namshi/jose allows the acceptance of unsecure JSON Web Signatures (JWS) by default. The vulnerability arises from the $allowUnsecure flag, which, when set to true during the loading of JWSes, permits tokens signed with 'none' algorithms to be processed. This behavior poses a significant security risk as it could allow an attacker to impersonate users by crafting a valid jwt token.
Several widely-used JSON Web Token (JWT) libraries, including node-jsonwebtoken, pyjwt, namshi/jose, php-jwt, and jsjwt, are affected by critical vulnerabilities that could allow attackers to bypass the verification step when using asymmetric keys (RS256, RS384, RS512, ES256, ES384, ES512).
It is possible for an attacker to create his own signed token with any payload he wants and have it considered valid using the "none" algorithm.
Critical vulnerabilities in JSON Web Token libraries.
Attackers able to impersonate users.