CVE-2026-26952: Pi-hole Web Interface has Stored HTML Injection via Local DNS Records (CNAME/Hosts) in data-tag Attribute

Severity: medium (CVSS 5.4 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.3% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-02-19 · updated 2026-06-17
Weakness: CWE-20

Description

Pi-hole Admin Interface is a web interface for managing Pi-hole, a network-level ad and internet tracker blocking application. Versions 6.4 and below are vulnerable to stored HTML injection through the local DNS records configuration page, which allows an authenticated administrator to inject code that is stored in the Pi-hole configuration and rendered every time the DNS records table is viewed. The populateDataTable() function contains a data variable with the full DNS record value exactly as entered by the user and returned by the API. This value is inserted directly into the data-tag HTML attribute without any escaping or sanitization of special characters. When an attacker supplies a value containing double quotes ("), they can prematurely “close” the data-tag attribute and inject additional HTML attributes into the element. Since Pi-hole implements a Content Security Policy (CSP) that blocks inline JavaScript, the impact is limited. This issue has been fixed in version 6.4.1.

Affected products

pi-hole web: before 6.4.1 — fixed in 6.4.1

How to fix

Upgrade to a fixed version: pi-hole web 6.4.1. Check the vendor advisory for mitigations.

References

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