Add Multiple Marker <= 1.2 - Missing Authorization Checks to Settings Update

The Add Multiple Marker plugin for WordPress is vulnerable authorization bypass in versions up to, and including, 1.2. This is due to lacking authentication checks on certain user functions like addmultiplemarker_save_maps_data() which is called via a nopriv AJAX action. This makes it possible for unauthenticated attackers to make plugin settings changes.