LiteSpeed Cache < 7.9.1 - Reflected XSS via ESI 'esi' Parameter

Description

The plugin is vulnerable to Reflected Cross-Site Scripting via the 'esi' parameter due to insufficient input sanitization and output escaping. This makes it possible for unauthenticated attackers to inject arbitrary web scripts in pages that execute if they can successfully trick a user into performing an action such as clicking on a link. Exploitation requires that the attacker supply a validly signed 'esi' value in the GET query string while submitting a separate attacker-controlled 'esi' payload as a POST body field, relying on PHP's default $_REQUEST merge order to have the POST value take precedence at the point of execution.