WP Fastest Cache <= 1.1.2 - Cross-Site Request Forgery via 'wpfc_purgecache_varnish_callback'

The WP Fastest Cache plugin for WordPress is vulnerable to Cross-Site Request Forgery in versions up to, and including, 1.1.2. This is due to missing or incorrect nonce validation on the wpfc_purgecache_varnish_callback function. This makes it possible for unauthenticated attackers to purge the varnish cache via a forged request granted they can trick a site administrator into performing an action such as clicking on a link.