The User Registration & Membership – Free & Paid Memberships, Subscriptions, Content Restriction, User Profile, Custom User Registration & Login Builder plugin for WordPress is vulnerable to Insecure Direct Object Reference in all versions up to, and including, 5.1.5. This is due to missing ownership validation on a user-controlled attachment ID, allowing the plugin to store and subsequently delete arbitrary media attachments without verifying that the referenced attachment belongs to the requesting user. This makes it possible for authenticated attackers, with subscriber-level access and above, to permanently delete arbitrary media attachments uploaded by any other user, including administrators.