CVE-2026-33406: Pi-hole has a Stored HTML attribute injection

Severity: medium (CVSS 6.1 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: yes
Published: 2026-04-06 · updated 2026-10-26
Weakness: CWE-79

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, configuration values from the /api/config endpoint are placed directly into HTML value="" attributes without escaping in settings-advanced.js, enabling HTML attribute injection. A double quote in any config value breaks out of the attribute context. JavaScript execution is blocked by the server's CSP (script-src 'self'), but injected attributes can alter element styling for UI redressing. The primary attack vector is importing a malicious teleporter backup, which bypasses per-field server-side validation. This vulnerability is fixed in 6.5.

Affected products

pi-hole web: from 6.0 through 6.4.1

References

https://github.com/pi-hole/web/security/advisories/GHSA-9rfm-c5g6-538p

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