Flatsome | Multi-Purpose Responsive WooCommerce Theme <= 3.18.7 - Authenticated (Contributor+) Stored Cross-Site Scripting via Multiple Shortcodes

The Flatsome theme for WordPress is vulnerable to Stored Cross-Site Scripting via the UX Countdown, Video Button, UX Video, UX Slider, UX Sidebar, and UX Payment Icons shortcodes in all versions up to, and including, 3.18.7 due to insufficient input sanitization and output escaping on user supplied attributes. This makes it possible for authenticated attackers, with contributor-level access and above, to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page.