Pi-hole Admin Interface is a web interface for managing Pi-hole, a network-level advertisement and internet tracker blocking application. Pi-hole Admin Interface versions 6.2.1 and earlier are vulnerable to reflected cross-site scripting (XSS) via a malformed URL path. The 404 error page includes the requested path in the class attribute of the body tag without proper sanitization or escaping. An attacker can craft a URL containing an onload attribute that will execute arbitrary JavaScript code in the browser when a victim visits the malicious link. If an attacker sends a crafted pi-hole link to a victim and the victim visits it, attacker-controlled JavaScript code is executed in the browser of the victim. This has been patched in version 6.3.