W3 Total Cache < 2.1.5 - Reflected XSS in Extensions Page (JS Context)

The plugin was affected by a reflected Cross-Site Scripting (XSS) issue within the "extension" parameter in the Extensions dashboard, when the 'Anonymously track usage to improve product quality' setting is enabled, as the parameter is output in a JavaScript context without proper escaping. This could allow an attacker, who can convince an authenticated admin into clicking a link, to run malicious JavaScript within the user's web browser, which could lead to full site compromise.

With the 'Anonymously track usage to improve product quality' settings (in the plugin General Settings) turned on, open the URL below

https://example.com/wp-admin/admin.php?page=w3tc_extensions&extension=%27-alert%28document.domain%29-%27