The Premium Addons for KingComposer plugin for WordPress is vulnerable to unauthorized modification and loss of data in versions up to, and including, 1.1.1. This is due to missing authorization and capability checks on the add_custom_sidebar() and remove_custom_sidebar() AJAX handlers, both of which are exposed through wp_ajax_nopriv_* hooks and write directly to the octagon_custom_sidebar option via update_option(). This makes it possible for unauthenticated attackers to create arbitrary custom widget areas or delete existing custom sidebars, which can cause widgets assigned to those areas to silently lose their registration and stop rendering.