RealHomes Memberships < 3.1.0 - Missing Authorization to Authenticated (Subscriber+) Membership Payment Bypass via 'ims_add_paypal_recurring_membership' AJAX Action

Description

The RealHomes Memberships plugin for WordPress is vulnerable to authorization bypass in all versions up to, and including, 3.0.9. This is due to the plugin not properly verifying that a user is authorized to perform an action. This makes it possible for authenticated attackers, with subscriber-level access and above, to grant themselves any premium membership tier without completing a PayPal transaction, generating a falsified active payment receipt and gaining unauthorized access to restricted property listing allowances.