Slider, Gallery, and Carousel by MetaSlider < 3.111.1 - Author+ Stored XSS via 'delay' Post Meta Setting

Description

The plugin is vulnerable to Stored Cross-Site Scripting via the 'delay' post meta setting, due to insufficient input sanitization and output escaping. This makes it possible for authenticated attackers, with custom-level access and above, to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page. The ml-slider custom post type is registered without custom capability restrictions and the ml-slider_settings meta key is unprotected, allowing Author-level users to set the malicious delay value via XML-RPC custom_fields when creating an ml-slider post.