The Flex Store Users plugin for WordPress is vulnerable to Privilege Escalation in all versions up to, and including, 1.1.0. This is due to the fsUserHandle::signup and the fsSellerRole::add_role_seller functions not restricting what user roles a user can register with. This makes it possible for unauthenticated attackers to supply the administrator role during registration and gain administrator access to the site. Note: The vulnerability can be exploited with the fs_type parameter if the Flex Store Seller plugin is also activated.
The product does not properly assign, modify, track, or check privileges for an actor, creating an unintended sphere of control for that actor.