The Booking System Trafft plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the `bookingWebsiteUrl` setting in all versions up to, and including, 1.0.17 due to a missing capability check on the `set_options` AJAX action when the plugin is operating in agency mode. The `trafftSetOptions()` handler verifies a nonce that is exposed to any authenticated user (it is printed inline on every admin page, including profile.php) but performs no capability check before calling `update_option('trafft_option', ['bookingWebsiteUrl' => ...])`. This setting is then used by `trafftAdminAssets()` to enqueue `<bookingWebsiteUrl>/embed.js` as a script on every front-end page that renders the booking shortcode. This makes it possible for authenticated attackers, with Subscriber-level access and above, to point the embed-script URL at an attacker-controlled origin and execute arbitrary JavaScript in the browser of every site visitor (including admins).