The Livemesh Addons for Beaver Builder plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the `labb_admin_ajax` AJAX action in all versions up to, and including, 3.9.2 due to missing authorization checks and insufficient input sanitization. The AJAX handler verifies a nonce but does not check user capabilities. This makes it possible for authenticated attackers with Subscriber-level access and above to modify plugin settings and inject malicious scripts that execute when administrators access the plugin settings page or when any user visits the frontend.