CVE-2026-33403 Pi-hole has a Reflected XSS / HTML injection in taillog.js

Medium 6.1 Published 6 Apr 2026 Updated 6 Apr 2026

An unauthenticated attacker can inject HTML via a crafted URL to steal credentials from the Pi-hole admin interface due to improper output encoding.

Exploited in the wild: Not known
Login needed: Not needed
Attackable: Over the internet
Victim action needed: A user has to click or open something
Fix: None listed

What is CVE-2026-33403?

CVE-2026-33403 is a medium-severity cross-site scripting vulnerability in pi-hole web, published on 6 Apr 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

Official description

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.

Weakness: CWE-79

Which versions are affected by CVE-2026-33403?

It affects 1 product.

Products include Pi-Hole Web Interface.

How do I fix CVE-2026-33403?

No fix has been published for CVE-2026-33403 yet. Limit exposure of the affected software until one is available.

Escape output for the context it lands in and set a strict Content Security Policy. Upgrading the affected component is the real fix. More about Cross-site scripting.

Is CVE-2026-33403 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-33403 exists.

Sources

Also known as GHSA-7xqw-r9pr-qv59.