CVE-2026-39849

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{"affected": [{"affectedData": [{"product": "FTL", "vendor": "pi-hole", "versions": [{"status": "affected", "version": "< 6.6.1"}]}], "source": "security-advisories@github.com"}], "configurations": [{"nodes": [{"cpeMatch": [{"criteria": "cpe:2.3:a:pi-hole:ftldns:6.6:*:*:*:*:*:*:*", "matchCriteriaId": "077AAD8F-CF91-4ECE-A446-731786C12D62", "vulnerable": true}], "negate": false, "operator": "OR"}]}], "cveTags": [], "descriptions": [{"lang": "en", "value": "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."}, {"lang": "es", "value": "Pi-hole FTL es el motor central del bloqueador de anuncios y rastreadores a nivel de red de Pi-hole. En versiones anteriores a la 6.6.1, el campo de configuraci\u00f3n 'dns.interface' en Pi-hole FTL aceptaba caracteres de nueva l\u00ednea sin validaci\u00f3n, permitiendo a un atacante inyectar directivas arbitrarias en el archivo de configuraci\u00f3n de dnsmasq generado. En instalaciones sin contrase\u00f1a de administrador configurada (el valor predeterminado para muchas implementaciones), la API de configuraci\u00f3n es totalmente accesible sin credenciales, permitiendo a un atacante adyacente a la red inyectar la carga \u00fatil, habilitar el servidor DHCP integrado y lograr la ejecuci\u00f3n arbitraria de comandos en el host la pr\u00f3xima vez que cualquier dispositivo en la red solicite una concesi\u00f3n DHCP. El valor inyectado se persiste en /etc/pihole/pihole.toml y sobrevive a los reinicios. La funci\u00f3n strncpy en la ruta del c\u00f3digo limita el campo de interfaz total a 31 bytes, pero cargas \u00fatiles como wlan0\\ndhcp-script=/tmp/p encajan dentro de esta restricci\u00f3n. La validaci\u00f3n de configuraci\u00f3n de dnsmasq introducida en FTL 6.6 solo verifica la validez sint\u00e1ctica, por lo que las directivas v\u00e1lidas inyectadas a trav\u00e9s de una nueva l\u00ednea pasan la validaci\u00f3n con \u00e9xito. Este problema ha sido solucionado en la versi\u00f3n 6.6.1."}], "id": "CVE-2026-39849", "lastModified": "2026-07-24T21:10:00.143", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "LOW", "attackVector": "NETWORK", "availabilityImpact": "HIGH", "baseScore": 8.8, "baseSeverity": "HIGH", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "privilegesRequired": "LOW", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H", "version": "3.1"}, "exploitabilityScore": 2.8, "impactScore": 5.9, "source": "nvd@nist.gov", "type": "Primary"}], "cvssMetricV40": [{"cvssData": {"Automatable": "NOT_DEFINED", "Recovery": "NOT_DEFINED", "Safety": "NOT_DEFINED", "attackComplexity": "LOW", "attackRequirements": "NONE", "attackVector": "NETWORK", "availabilityRequirement": "NOT_DEFINED", "baseScore": 8.7, "baseSeverity": "HIGH", "confidentialityRequirement": "NOT_DEFINED", "exploitMaturity": "NOT_DEFINED", "integrityRequirement": "NOT_DEFINED", "modifiedAttackComplexity": "NOT_DEFINED", "modifiedAttackRequirements": "NOT_DEFINED", "modifiedAttackVector": "NOT_DEFINED", "modifiedPrivilegesRequired": "NOT_DEFINED", "modifiedSubAvailabilityImpact": "NOT_DEFINED", "modifiedSubConfidentialityImpact": "NOT_DEFINED", "modifiedSubIntegrityImpact": "NOT_DEFINED", "modifiedUserInteraction": "NOT_DEFINED", "modifiedVulnAvailabilityImpact": "NOT_DEFINED", "modifiedVulnConfidentialityImpact": "NOT_DEFINED", "modifiedVulnIntegrityImpact": "NOT_DEFINED", "privilegesRequired": "LOW", "providerUrgency": "NOT_DEFINED", "subAvailabilityImpact": "NONE", "subConfidentialityImpact": "NONE", "subIntegrityImpact": "NONE", "userInteraction": "NONE", "valueDensity": "NOT_DEFINED", "vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X", "version": "4.0", "vulnAvailabilityImpact": "HIGH", "vulnConfidentialityImpact": "HIGH", "vulnIntegrityImpact": "HIGH", "vulnerabilityResponseEffort": "NOT_DEFINED"}, "source": "security-advisories@github.com", "type": "Secondary"}], "ssvcV203": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "ssvcData": {"id": "CVE-2026-39849", "options": [{"exploitation": "poc"}, {"automatable": "no"}, {"technicalImpact": "total"}], "role": "CISA Coordinator", "timestamp": "2026-05-08T03:55:36.195107Z", "version": "2.0.3"}}]}, "published": "2026-05-05T21:16:22.677", "references": [{"source": "security-advisories@github.com", "tags": ["Patch"], "url": "https://github.com/pi-hole/FTL/commit/0c46e4ec7fe57f762fce261625f2cf5d43806e6d"}, {"source": "security-advisories@github.com", "tags": ["Product", "Release Notes"], "url": "https://github.com/pi-hole/FTL/releases/tag/v6.6.1"}, {"source": "security-advisories@github.com", "tags": ["Exploit", "Vendor Advisory"], "url": "https://github.com/pi-hole/FTL/security/advisories/GHSA-9cqv-839p-gpq2"}, {"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "tags": ["Exploit", "Vendor Advisory"], "url": "https://github.com/pi-hole/FTL/security/advisories/GHSA-9cqv-839p-gpq2"}], "sourceIdentifier": "security-advisories@github.com", "vulnStatus": "Analyzed", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-93"}], "source": "security-advisories@github.com", "type": "Secondary"}]}

{}

{"affected": [{"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "[0,6.6.1)"}}], "enrichment": {"confidence": 88.0, "confidence_source": "matching", "scores": [{"score": 88.0, "source": "matching"}]}, "original": {"product": "FTL", "source": "cna", "vendor": "pi-hole"}, "product": "ftldns", "vendor": "pi-hole"}], "created": "2026-05-05T22:30:33.619178+00:00", "updated": "2026-05-06T09:00:09.728939+00:00", "vendors": ["pi-hole", "pi-hole$PRODUCT$ftldns"]}