T4G0

**Name of the Vulnerable Software and Affected Versions** Mstore Api plugin for WordPress versions prior to 4.20.1 **Description** An authentication bypass exists due to JWT (JSON Web Token) forgery. The issue occurs in the `FirebasePhoneAuthHelper::verify id token()` function, which validates token claims such as `alg`, `kid`, `aud`, and `iss` but fails to perform cryptographic signature verification using `openssl verify()` or an equivalent method against Google's public key certificates. This allows unauthenticated attackers to use a self-generated RSA key pair to forge a Firebase Phone Auth JWT and impersonate any phone number, leading to unauthorized access to existing accounts or the creation of arbitrary new accounts. **Recommendations** Update the Mstore Api plugin for WordPress to a version newer than 4.20.0.