User Registration & Membership <= 5.1.4 - Missing Authorization to Authenticated (Contributor+) Content Access Rule Manipulation

The User Registration & Membership plugin for WordPress is vulnerable to unauthorized modification of data due to a missing capability check on the Content Access Rules REST API endpoints in versions 5.0.1 through 5.1.4. This is due to the `check_permissions()` method only checking for `edit_posts` capability instead of an administrator-level capability. This makes it possible for authenticated attackers, with Contributor-level access and above, to list, create, modify, toggle, duplicate, and delete site-wide content restriction rules, potentially exposing restricted content or denying legitimate user access.