Live CSS Preview < 2.1.5 - Missing Authorization to Authenticated (Subscriber+) Settings Update

Description

The Live CSS Preview plugin for WordPress is vulnerable to unauthorized modification of data due to a missing capability check on the 'wp_ajax_frontend_save' AJAX endpoint in all versions up to, and including, 2.1.4. This makes it possible for authenticated attackers, with Subscriber-level access and above, to update the plugin's css setting.