The Frontis Blocks plugin for WordPress is vulnerable to Server-Side Request Forgery in all versions up to, and including, 1.1.6. This is due to insufficient restriction on the 'url' parameter in the 'template_proxy' function. This makes it possible for unauthenticated attackers to make web requests to arbitrary locations originating from the web application via the '/template-proxy/' and '/proxy-image/' endpoint.
https://plugins.trac.wordpress.org/changeset/3444616/
https://plugins.trac.wordpress.org/browser/frontis-blocks/trunk/includes/Admin/Admin.php#L910
https://plugins.trac.wordpress.org/browser/frontis-blocks/tags/1.1.4/includes/Admin/Admin.php#L910