In Firebase PHP-JWT before 6.0.0, an algorithm-confusion issue (e.g., RS256 / HS256) exists via the kid (aka Key ID) header, when multiple types of keys are loaded in a key ring. This allows an attacker to forge tokens that validate under the incorrect key. NOTE: this provides a straightforward way to use the PHP-JWT library unsafely, but might not be considered a vulnerability in the library itself.

The Simple JWT Login WordPress plugin before 3.3.0 can be used to create new WordPress user accounts with a randomly generated password. The password is generated using the str_shuffle PHP function that "does not generate cryptographically secure values, and should not be used for cryptographic purposes" according to PHP's documentation.

The Simple JWT Login WordPress plugin before 3.2.1 does not have nonce checks when saving its settings, allowing attackers to make a logged in admin changed them. Settings such as HMAC verification secret, account registering and default user roles can be updated, which could result in site takeover.

JWT is a library to work with JSON Web Token and JSON Web Signature. Prior to versions 3.4.6, 4.0.4, and 4.1.5, users of HMAC-based algorithms (HS256, HS384, and HS512) combined with `Lcobucci\JWT\Signer\Key\LocalFileReference` as key are having their tokens issued/validated using the file path as hashing key - instead of the contents. The HMAC hashing functions take any string as input and, since users can issue and validate tokens, users are lead to believe that everything works properly. Versions 3.4.6, 4.0.4, and 4.1.5 have been patched to always load the file contents, deprecated the `Lcobucci\JWT\Signer\Key\LocalFileReference`, and suggest `Lcobucci\JWT\Signer\Key\InMemory` as the alternative. As a workaround, use `Lcobucci\JWT\Signer\Key\InMemory` instead of `Lcobucci\JWT\Signer\Key\LocalFileReference` to create the instances of one's keys.

NATS Server 2.x before 2.2.0 and JWT library before 2.0.1 have Incorrect Access Control because Import Token bindings are mishandled.

jwt-go before 4.0.0-preview1 allows attackers to bypass intended access restrictions in situations with []string{} for m["aud"] (which is allowed by the specification). Because the type assertion fails, "" is the value of aud. This is a security problem if the JWT token is presented to a service that lacks its own audience check.

In express-jwt (NPM package) up and including version 5.3.3, the algorithms entry to be specified in the configuration is not being enforced. When algorithms is not specified in the configuration, with the combination of jwks-rsa, it may lead to authorization bypass. You are affected by this vulnerability if all of the following conditions apply: - You are using express-jwt - You do not have **algorithms** configured in your express-jwt configuration. - You are using libraries such as jwks-rsa as the **secret**. You can fix this by specifying **algorithms** in the express-jwt configuration. See linked GHSA for example. This is also fixed in version 6.0.0.

Xmidt cjwt through 1.0.1 before 2019-11-25 maps unsupported algorithms to alg=none, which sometimes leads to untrusted accidental JWT acceptance.

The json-jwt gem before 1.11.0 for Ruby lacks an element count during the splitting of a JWE string.

Connect2id Nimbus JOSE+JWT before v7.9 can throw various uncaught exceptions while parsing a JWT, which could result in an application crash (potential information disclosure) or a potential authentication bypass.