The Master Slider – Responsive Touch Slider plugin for WordPress is vulnerable to Cross-Site Request Forgery in all versions up to, and including, 3.9.3. This is due to missing or incorrect nonce validation on the 'process_bulk_action' function. This makes it possible for unauthenticated attackers to duplicate or delete arbitrary sliders via a forged request granted they can trick a site administrator into performing an action such as clicking on a link.