Opal Estate Pro <= 1.7.5 - Unauthenticated Privilege Escalation via 'on_regiser_user'

The Opal Estate Pro – Property Management and Submission plugin for WordPress, used by the FullHouse - Real Estate Responsive WordPress Theme, is vulnerable to privilege escalation via in all versions up to, and including, 1.7.5. This is due to a lack of role restriction during registration in the 'on_regiser_user' function. This makes it possible for unauthenticated attackers to arbitrarily choose the role, including the Administrator role, assigned when registering.