Jwt-Library >= 4.0.0, < 4.0.7

A Time-of-Check/Time-of-Use (TOCTOU) vulnerability exists in the `JWSVerifier` and `JWEDecrypter` components of the `web-token/jwt-framework` and `web-token/jwt-library` PHP packages, allowing an attacker to override the integrity-protected `alg` parameter from the unprotected header, leading to authentication bypass and unauthorized access.