ProfileGrid <= 5.9.8.4 - Missing Authorization to Authenticated (Subscriber+) Arbitrary Group Joining

The ProfileGrid – User Profiles, Groups and Communities plugin for WordPress is vulnerable to unauthorized access due to a missing capability check on the pm_invite_user function in all versions up to, and including, 5.9.8.4. This makes it possible for authenticated attackers, with Subscriber-level access and above, to add themselves or any registered user to any ProfileGrid group, including closed and paid groups, bypassing all authorization and payment gates.