XSS in Pi-Hole Web
CVE-2026-33403
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.
Vulnerability class: XSS (Cross-Site Scripting)
EPSS: 0.002 (8.4th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 6.1 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N.
Affected products
- Pi-hole Web — versions >= 6.0, < 6.5
- Pi-hole Web_interface
Weakness classification (CWE)
References
- security-advisories@github.com (x_refsource_CONFIRM, Vendor Advisory)
Frequently asked questions
- What is CVE-2026-33403?
- CVE-2026-33403 is a medium-severity vulnerability in Pi-Hole Web, classified under Cross-site Scripting. CVSS score: 6.1/10. Published 2026-04-06.
- How severe is CVE-2026-33403?
- Medium severity. CVSS v3 base score is 6.1 out of 10.