The WP Chat App plugin for WordPress is vulnerable to unauthorized plugin installation due to a missing capability check on the ajax_install_plugin() function in all versions up to, and including, 3.6.8. This makes it possible for authenticated attackers, with Subscriber-level access and above, to install the filebird plugin.
https://plugins.trac.wordpress.org/changeset/3186930/wp-whatsapp/trunk/includes/Cross.php
https://plugins.trac.wordpress.org/browser/wp-whatsapp/trunk/includes/Cross.php#L206
https://plugins.trac.wordpress.org/browser/wp-whatsapp/tags/3.6.7/includes/Cross.php#L206