The Master Slider – Responsive Touch Slider plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the slides callback functionality in all versions up to, and including, 3.9.5. This makes it possible for authenticated attackers, with editor-level access, to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page. This only affects multi-site installations and installations where unfiltered_html has been disabled.