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Pi-hole FTL CVE-2026-44693

HIGH
Race Condition (CWE-362)
2026-06-10 GitHub_M
8.8
CVSS 3.1 · Vendor: GitHub_M
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Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain

  1. Access
    Identify exposed Pi-hole admin interface
  2. Delivery
    Wait for or induce admin login activity
  3. Exploit
    Send concurrent HTTP session requests
  4. Execution
    Win race in CivetWeb session handler
  5. Persist
    Hijack authenticated session context
  6. Impact
    Modify DNS filtering or exfiltrate query logs

Vulnerability Assessment

Weakness
CWE
OWASP Top 10:2025
A06:2025 - Insecure Design
ASVS 5.0
V15 - Secure Coding and Architecture Concurrency control, locking
MITRE ATT&CK

1 technique across 1 tactic: Privilege Escalation

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

Exploitation Conditions

Exploitation requires that the Pi-hole FTL embedded CivetWeb-based web admin interface (introduced in v6.0) be network-reachable by the attacker and that a legitimate administrator be concurrently authenticated and actively generating HTTP requests against it - the UI:R metric reflects this required admin interaction. The race window exists in the HTTP session management code path, so an attacker must be able to issue multiple overlapping HTTP requests timed against the admin's session activity; instances where the admin UI is bound to localhost only, firewalled to management subnets, or simply idle during the attack window are not practically exploitable. Versions prior to v6.0 (which used the older web stack) and v6.6.1 or later are not affected.

Impact

The CVSS 3.1 vector AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H rates this 8.8 (High), reflecting network reachability, low attack complexity, no privileges required, but mandatory user interaction - typically meaning a legitimate admin must be actively using the web UI for the race to be winnable. EPSS and CISA KEV data were not provided in the input; absence is not confirmation either way, but no public exploit identified at time of analysis and the vulnerability was reported through a coordinated GitHub Security Advisory rather than after observed exploitation. Race-condition session bugs are notoriously timing-sensitive and reliability of exploitation in production environments tends to be far lower than the raw 8.8 score implies, so this is best treated as a meaningful but not emergency priority - patch within a normal maintenance window, prioritizing internet-exposed Pi-hole instances. The CVSS UI:R requirement and reliance on concurrent admin activity are the main mitigating factors against widespread automated exploitation.

Exploit ScenarioDerived

An attacker on the same network as a Pi-hole instance - or able to reach an exposed admin interface - sends concurrent HTTP requests timed to coincide with an authenticated admin browsing the web UI, racing the session management code to either hijack the admin's session cookie state or assume their authenticated context. Once the race is won, the attacker can modify DNS blocklists, disable filtering, exfiltrate query logs revealing browsed domains, or pivot the Pi-hole into a DNS-based man-in-the-middle position. No public proof-of-concept is identified at time of analysis, and successful exploitation requires winning a timing window during real admin activity.

This Week Schedule remediation this week. Why: HIGH severity (CVSS 7.0-8.9).
No patch listed yet 0.0% exploitation probability (EPSS)

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AnalysisAIv1 – Jun 10, 2026

Session hijacking in Pi-hole FTL versions prior to 6.6.1 stems from a race condition in the CivetWeb-based HTTP session management subsystem introduced during the v6.0 rewrite. Remote attackers can leverage concurrent requests to compromise web admin session state, potentially gaining high-impact access (C:H/I:H/A:H per CVSS 8.8) to the DNS sinkhole and network filtering controls. No public exploit identified at time of analysis, but vendor has published an upstream fix in v6.6.1.

RemediationAI

Vendor-released patch: upgrade Pi-hole FTL to version 6.6.1 or later, available at https://github.com/pi-hole/FTL/releases/tag/v6.6.1, with full advisory details at https://github.com/pi-hole/FTL/security/advisories/GHSA-9ff5-f3v5-2xc7. Until the upgrade is applied, restrict access to the Pi-hole web admin interface (default TCP/80 and /admin path) to trusted management networks via firewall rules or by binding the embedded web server to localhost only, accepting that this disables remote administration; additionally, avoid keeping multiple concurrent admin browser sessions open simultaneously, since the race requires overlapping HTTP session activity, though this is operationally inconvenient rather than a hard fix. Do not rely on disabling the API while leaving the web UI exposed, as the underlying CivetWeb session subsystem is shared.

Affects your stack

Find out whether the stacks and servers you run are on an affected version.

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

Technical ContextAI · show details

Pi-hole FTL (Faster Than Light) is the C-based daemon at the heart of Pi-hole, handling DNS resolution, query logging, and the embedded administrative web interface. Since version 6.0, the project replaced its prior web stack with CivetWeb, an embedded HTTP server library, and the HTTP session management code introduced in that rewrite contains a CWE-362 concurrent-execution race condition. Race conditions in session subsystems typically arise from unsynchronized access to session token tables, cookie-to-session mappings, or per-session state structures, where two concurrent requests can interleave reads and writes such that one client observes or hijacks another's session context. The v6.6.1 release notes corroborate this, citing PR #2835 'thread-safety issues causing SIGSEGV under concurrent API load,' PR #2833 'rare race condition for SHM strings in API handlers,' and PR #2847 'thread-safety for concurrent API requests,' indicating broader concurrency hardening around the API surface.

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Severity by source

Vendor (GitHub_M) PRIMARY 8.8 HIGH
AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
vuln.today AI 7.5 HIGH

Network-reachable admin UI (AV:N), no auth needed by attacker (PR:N), but UI:R for concurrent admin activity and AC:H since race-window timing is non-trivial; full session compromise yields C/I/A:H.

3.1 AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H
4.0 AV:N/AC:H/AT:N/PR:N/UI:A/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

Primary rating from Vendor (GitHub_M).

CVSS VectorVendor: GitHub_M

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

DescriptionCVE.org

Pi-hole FTL is the core engine of the Pi-hole network-level advertisement and tracker blocker. Prior to version 6.6.1, Pi-hole FTL contains a race condition vulnerability in the HTTP session management subsystem, introduced with the v6.0 rewrite of the embedded CivetWeb-based web server. This issue has been patched in version 6.6.1.

Executive ViewAI

Why It Matters

A high-severity vulnerability in Pi-hole FTL versions prior to 6.6.1 allows remote attackers to hijack administrator sessions and compromise DNS filtering controls; no public exploit code has been identified at time of analysis. Organizations deploying Pi-hole face potential network traffic manipulation, spoofing, and loss of DNS-based malware protection. Immediate upgrade to version 6.6.1 is required to restore network security posture.

Business Impact: High
Compensating Controls

Vendor-released patch: Pi-hole FTL v6.6.1. Restrict network access to administrative interface to trusted networks only and monitor for suspicious administrative activity until patching is complete.

Threat Intelligence Overview

EPSS Score
0.0%
Top 89% exploitable
Social Media
2
Sightings
Data Quality
6 sources
Confidence: High
NVD CVE.org EPSS Vulnrichment CIRCL 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 HIGH
CISA KEV No
Public POC No
EPSS 0.0%
Patch available No
Active threat No
Deciding rule
HIGH severity (CVSS 7.0-8.9)
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
Scheduled
Exploitation
Poc
System Exposure· derived
Open
Automatable
No
Human Impact
High
Technical Impact
Total

Priority Score

44
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +44
PoC: 0
Weaponized: 0
Threat intel: 0
Gov advisory: 0

Attack Technique

Information disclosure occurs when an application unintentionally exposes sensitive data that aids attackers in reconnaissance or directly compromises security.

Race conditions occur when multiple concurrent requests exploit the brief time gap between checking a condition and acting upon it (TOCTOU - Time of Check, Time of Use).

Affected Products (CPE)CVE.org

cpe:2.3:a:pi-hole:ftl:*:*:*:*:*:*:*:*

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