UserPro <= 5.1.0 - Cross-Site Request Forgery to PHP Object Injection

The UserPro plugin for WordPress is vulnerable to Cross-Site Request Forgery in versions up to, and including, 5.1.0. This is due to missing or incorrect nonce validation on the 'import_settings' function. This makes it possible for unauthenticated attackers to exploit PHP Object Injection due to the use of unserialize() on the user supplied parameter via a forged request granted they can trick a site administrator into performing an action such as clicking on a link.