The MStore API plugin for WordPress is vulnerable to authentication bypass in versions up to, and including, 2.1.5. This is due to unrestricted access to the 'register' and 'update_user_profile' routes. This makes it possible for unauthenticated attackers to create new administrator accounts, delete existing administrator accounts, or escalate privileges on any account.
The product does not perform any authentication for functionality that requires a provable user identity or consumes a significant amount of resources.