RT Mega Menu < 1.5.2 - Subscriber+ Stored XSS via Menu Item CSS

Description

The plugin does not perform a capability check on the AJAX action that saves mega-menu configuration and per-menu-item settings; its only gate is a nonce that any logged-in user can read from a standard admin page. A subscriber-level user can therefore enable the mega menu on a site menu and store a menu-item style value that is rendered, without output escaping, into a style attribute on the public navigation. By breaking out of that attribute the user persists a JavaScript event handler that executes for every visitor who hovers the navigation, including administrators, leading to session/site takeover.