CVE-2026-39849: Pi-hole FTL is the core engine of the Pi-hole network-level advertisement and tracker blocker

This month

HIGH 8.8DOWNGRADE

CVE-2026-39849 is a high-severity flaw (CVSS 8.8) affecting ftldns. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Pi-hole FTL is the core engine of the Pi-hole network-level advertisement and tracker blocker. In versions before 6.6.1, the `dns.interface` configuration field in Pi-hole FTL accepted newline characters without validation, allowing an attacker to inject arbitrary directives into the generated dnsmasq configuration file. On installations with no admin password set (the default for many deployments), the configuration API is fully accessible witho

Why this priority

High severity
Public exploit reference

No fix is published yet: follow the downgrade or mitigation steps.

Risk facts

CVSS score	8.8 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	Low
User interaction	None
EPSS exploit chance	1.0% (top 39%)
CISA exploited list	No
Weakness	CWE-93
Published	2026-05-05
Last modified	2026-07-24

Publisher (CNA): GitHub, Inc. · Vendor: pi-hole

Last updated 2026-07-24 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-05-05 21:16 UTCPublished CVE record published
2026-07-24 21:10 UTCUpdated Record last modified

pi-hole ftldns DOWNGRADE

Affected: 6.6

Fixed in: no fixed release known

Safe to downgrade to: a release before 6.6

1. Check installed version

apt-cache policy ftldns || rpm -q ftldns || ftldns --version

2. No fixed release: DOWNGRADE to a release before 6.6 (Debian / Ubuntu)

apt-cache madison ftldns sudo apt install ftldns=<VERSION_BEFORE_6.6> sudo apt-mark hold ftldns

2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list ftldns sudo dnf downgrade ftldns-<VERSION_BEFORE_6.6> sudo dnf versionlock add ftldns

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-39849?

ftldns: downgrade or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2026-39849 being exploited?

CVE-2026-39849 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-39849 affect?

CVE-2026-39849 affects ftldns. Severity is high (CVSS 8.8). Pi-hole FTL is the core engine of the Pi-hole network-level advertisement and tracker blocker. In versions before 6.6.1, the `dns.interface` configuration field in Pi-hole FTL accepted newline characters without validation, allowing an atta

How urgent is CVE-2026-39849?

Priority 51/100. High severity; Public exploit reference

Software pages

Dnsmasq vulnerabilities

Related CVEs

CVE-2026-35517 HIGH 8.8 UPGRADE FTLDNS (pihole-FTL) provides an interactive API and also generates statistics for Pi-hole's Web interface
CVE-2026-35491 MEDIUM 6.1 UPGRADE FTLDNS (pihole-FTL) provides an interactive API and also generates statistics for Pi-hole's Web interface
CVE-2026-35518 HIGH 8.8 UPGRADE FTLDNS (pihole-FTL) provides an interactive API and also generates statistics for Pi-hole's Web interface
CVE-2026-35520 HIGH 8.8 UPGRADE FTLDNS (pihole-FTL) provides an interactive API and also generates statistics for Pi-hole's Web interface
CVE-2026-35521 HIGH 8.8 UPGRADE FTLDNS (pihole-FTL) provides an interactive API and also generates statistics for Pi-hole's Web interface

References

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