Nextend Social Login and Register <= 3.1.21 - Cross-Site Request Forgery to Unlink User Social Login

The Nextend Social Login and Register plugin for WordPress is vulnerable to Cross-Site Request Forgery in all versions up to, and including, 3.1.21. This is due to missing or incorrect nonce validation on the 'unlinkUser' function. This makes it possible for unauthenticated attackers to unlink the user's social login via a forged request granted they can trick a site administrator into performing an action such as clicking on a link.