The RegistrationMagic plugin for WordPress is vulnerable to Insecure Direct Object References in versions up to, and including, 5.2.0.5. This is due to the plugin providing user-controlled access to objects, letting a user bypass authorization and access system resources. This makes it possible for authenticated attackers, with administrator-level permissions and above, to change user passwords and potentially take over super-administrator accounts in multisite setup.
The system's authorization functionality does not prevent one user from gaining access to another user's data or record by modifying the key value identifying the data.