Expire Users <= 1.2.2 - Authenticated (Subscriber+) Privilege Escalation to Administrator via save_extra_user_profile_fields

The Expire Users plugin for WordPress is vulnerable to Privilege Escalation in all versions up to, and including, 1.2.2. This is due to the plugin allowing a user to update the 'on_expire_default_to_role' meta through the 'save_extra_user_profile_fields' function. This makes it possible for authenticated attackers, with Subscriber-level access and above, to elevate their privileges to that of an administrator.