Download Panel <= 1.3.3 - Missing Authorization to Authenticated (Subscriber+) Arbitrary Plugin Settings Modification

The Download Panel plugin for WordPress is vulnerable to unauthorized settings modification due to a missing capability check on the 'wp_ajax_save_settings' AJAX action in all versions up to, and including, 1.3.3. This is due to the absence of any capability verification in the `dlpn_save_settings()` function. This makes it possible for authenticated attackers, with Subscriber-level access and above, to arbitrarily modify plugin settings including display text, download links, button colors, and other visual customizations.