Pi-hole Admin Interface is a web interface for managing Pi-hole, a network-level ad and internet tracker blocking application. From 6.0 to before 6.5, a reflected DOM-based XSS vulnerability in taillog.js allows an unauthenticated attacker to inject arbitrary HTML into the Pi-hole admin interface by crafting a malicious URL. The file query parameter is interpolated into an innerHTML assignment without escaping. Because the Content-Security-Policy is missing the form-action directive, injected <form> elements can exfiltrate credentials to an external origin. This vulnerability is fixed in 6.5.
Use CWE-79, Pi-Hole vendor hub and Web Interface product page to widen CVE-2026-33403 into its surrounding weakness, vendor, and product context.
Compare it with CVE-2026-33765, CVE-2023-23614 and CVE-2025-59151 for nearby disclosures in the same product family.