CVE-2026-39849
HighCVSS 8.8Exploitation Probability (EPSS)
Elevated risk58th percentile - higher than 58% of all known CVEs
Summary
In Pi-hole FTL before version 6.6.1, the `dns.interface` configuration field accepts newline characters without validation, allowing an attacker to inject directives into the dnsmasq config file. On installations without an admin password, a network-adjacent attacker can enable the built-in DHCP server and achieve remote code execution on the next DHCP lease request. Fixed in version 6.6.1.
Risk Assessment
An attacker can achieve remote code execution on the Pi-hole host, leading to full device compromise and potential network takeover.
Recommendation
Upgrade Pi-hole FTL to version 6.6.1 or later.
Other vulnerabilities in Pi-hole FTL
Original NVD description (English source)
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 without credentials, allowing a network-adjacent attacker to inject the payload, enable the built-in DHCP server, and achieve arbitrary command execution on the host the next time any device on the network requests a DHCP lease. The injected value is persisted to /etc/pihole/pihole.toml and survives restarts. The strncpy in the code path limits the total interface field to 31 bytes, but payloads such as wlan0\ndhcp-script=/tmp/p fit within this constraint. The dnsmasq config validation introduced in FTL 6.6 only checks syntactic validity, so valid directives injected via newline pass validation successfully. This issue has been fixed in version 6.6.1.