CVE-2026-4267: The Query Monitor plugin for WordPress has Reflected Cross-Site Scripting via Request URI

The Query Monitor plugin for WordPress is vulnerable to Reflected Cross-Site Scripting via the $_SERVER['REQUEST_URI'] parameter in all versions up to, and including, 3.20.3 due to insufficient output escaping. This makes it possible for unauthenticated attackers to inject arbitrary web scripts in pages that execute if they can successfully trick an Administrator-level user into performing an action such as clicking on a link.

On admin requests, the plugin reads user controlled data from $_SERVER['REQUEST_URI'] and stores it in the request field, then renders request, matched_query, and query_string through format_url(). If the attacker supplied string does not contain &, format_url() returns it without HTML escaping, which allows injected HTML or JavaScript from the request target to be inserted directly into the page inside a <code> element and executed in the victim’s browser.