The Mstore Api plugin for WordPress is vulnerable to Authentication Bypass via JWT Forgery in versions up to, and including, 4.20.0 This is due to missing cryptographic signature verification in the FirebasePhoneAuthHelper::verify_id_token() function, which decodes and validates Firebase ID token claims (alg, kid, aud, iss) but never calls openssl_verify() or any equivalent to validate the JWT signature against Google's actual public key certificates. This makes it possible for unauthenticated attackers to forge a Firebase Phone Auth JWT signed with a self-generated RSA key pair and impersonate any phone number, resulting in unauthorized access to existing WordPress accounts or creation of new arbitrary accounts.

The Mstore API plugin for WordPress (versions up to and including 4.20.0) contains a critical authentication bypass vulnerability via JWT forgery. The vulnerability exists in the FirebasePhoneAuthHelper::verify_id_token() function, which validates Firebase ID token claims but never performs cryptographic signature verification using openssl_verify() or equivalent. This allows unauthenticated attackers to forge Firebase Phone Auth JWTs using self-generated RSA key pairs, enabling impersonation of any phone number. Successful exploitation can result in unauthorized access to existing WordPress accounts or creation of arbitrary new accounts. The flaw is classified as a missing cryptographic signature verification issue, making it exploitable without any prior authentication.