W3 Total Cache < 2.10.7 - Unauthenticated Stored XSS via Comment Content

Description

The plugin is vulnerable to Stored Cross-Site Scripting via comment content, due to insufficient input sanitization and output escaping in its output-buffer regex rewrite, allowing unauthenticated attackers to inject arbitrary web scripts into pages that execute whenever a user accesses an injected page. This is only exploitable when the 'Remove query strings from static resources' option is enabled, as mutate_url() must strip the '?' delimiter and everything following it, including the closing quote of the outer attribute, to break the attribute boundary.