Evidence used
- No CISA KEV confirmation is currently recorded.
- A structured source references public exploit or proof-of-concept material.
- EPSS is 1.00% for the current model date.
BlackTreeCVE IntelligenceFull vulnerability report · 2026
CVE-2026-39849High confidence
Pi-hole FTL remote code execution via newline injection in dns.interface configuration
pi-hole · FTL
Official source article: GitHub GHSA-9CQV-839P-GPQ2 ↗. Check the applicable product and release in the original source.
8.7HighCVSS 4.0
Within 7 days
Patch availableHigh technical severity with public exploit material referenced by a structured source; prioritise exposed affected systems while verifying vendor guidance.
R
Open reassessment dashboard →Operational reassessment
Published severity in operational context
Published severityHigh→Operational priority:Critical, raised one band.upgradedsince 8 May 2026
Compensating controls
- Validate the affected product branch and deploy the verified fixed release.
- Restrict the affected network interface to trusted sources where business-safe.
- Increase monitoring for the attack path and post-exploitation behaviour described in the report.
Verification
- Confirm that the asset runs pi-hole FTL and falls inside the recorded affected range.
- Verify the installed build against the product-specific fixed version after deployment.
- Validate exposure, authentication requirements and compensating controls in the actual environment.
- Reopen this reassessment when CVSS, KEV, EPSS, exploit evidence or remediation changes.
High technical severity with public exploit material referenced by a structured source; prioritise exposed affected systems while verifying vendor guidance.
Patch available01
What, why and how
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.
What
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.
Why
The product uses CRLF (carriage return line feeds) as a special element, e.g. to separate lines or records, but it does not neutralize or incorrectly neutralizes CRLF sequences from inputs.
How
An attacker operating through a network path may attempt exploitation with low privileges. If successful, the issue may cause the confidentiality, integrity or availability impact described by the vendor.
What
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.
Why
The product uses CRLF (carriage return line feeds) as a special element, e.g. to separate lines or records, but it does not neutralize or incorrectly neutralizes CRLF sequences from inputs.
How
An attacker operating through a network path may attempt exploitation with low privileges. If successful, the issue may cause the confidentiality, integrity or availability impact described by the vendor.
02
Exploit reality and attack path
CVSS severity, EPSS forecast probability, public exploit material and CISA-confirmed exploitation are separate signals.
Observed exploitation No confirmed evidence
?
Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.No CISA KEV match was present at the last successful refresh. This means no confirmation from that source, not proof of no exploitation.
Public PoC / exploit material Reference recorded
?
Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.A structured CVE source labels at least one public reference as exploit material. BlackTree has not independently validated that it is safe, reliable or weaponised.
- Likely attack path
- a network path → Improper Neutralization of CRLF Sequences ('CRLF Injection') → cause the confidentiality, integrity or availability impact described by the vendor
- Attack surface
- Network
- Privileges required
- Low: a basic authenticated account is required
- User interaction
- None
- Attack complexity
- Low: no specialised conditions are recorded
- Security boundary
- Not a CVSS 4.0 base metric
- Weakness
?
CWE means Common Weakness Enumeration: a standard category for the underlying weakness. - CWE-93 ↗
CWE-93: Improper Neutralization of CRLF Sequences ('CRLF Injection'). The product uses CRLF (carriage return line feeds) as a special element, e.g. to separate lines or records, but it does not neutralize or incorrectly neutralizes CRLF sequences from inputs.
- CVSS vector
?
CVSS means Common Vulnerability Scoring System. The vector records the metric values used to calculate technical severity. CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:NCommon Vulnerability Scoring System 4.0: the compact vector below is decoded into plain language.
AVNetworkAttack vector: The vulnerable component can be reached over a network.ACLowAttack complexity: No specialised conditions are required beyond attacker-controlled input.ATNoneAttack requirements: No additional deployment or execution condition is required.PRLowPrivileges required: The attacker needs basic user-level privileges.UINoneUser interaction: No action by another user is required.VCHighVulnerable-system confidentiality: A successful attack can cause a major loss.VIHighVulnerable-system integrity: A successful attack can cause a major loss.VAHighVulnerable-system availability: A successful attack can cause a major loss.SCNoneSubsequent-system confidentiality: No direct loss is represented by this metric.SINoneSubsequent-system integrity: No direct loss is represented by this metric.SANoneSubsequent-system availability: No direct loss is represented by this metric.- Post-exploitation / living off the land
- Stolen credentials, tokens and legitimate administration functions may provide continued access without deploying a large custom toolset.
03
Patch and workaround
Operational remediation based on structured source evidence.
- Status
?
Patch availability is based on structured fixed-version fields and authoritative update references. If no fix is verified, check the vendor advisory before making a change. - Patch available
- Affected
- FTL: < 6.6.1
- Fixed
- 6.6.1.
- Action
- Review the linked authoritative reference and apply the recorded fixed release appropriate to the affected product branch.
- Workaround
- No verified workaround is recorded. If business-safe, reduce exposure to the affected interface and allow only trusted sources until authoritative guidance is available.
04
Evidence and provenance
Published 5 May 2026 · Last source change 8 May 2026, 14:12 UTC · CWE-93 · Improper Neutralization of CRLF Sequences ('CRLF Injection')
CVE recordCVE.org · 5.2
CVSS sourceCNA
EPSS source FIRST · tracked since 2026-08-14
?
The date BlackTree first stored a score for this CVE from the daily FIRST EPSS feed.European sourceENISA EUVD · EUVD-2026-27498
Product sourceCNA
Remediation sourceCVE/CNA references
CWE sourceCNA
NVD statusNVD enriched
Core structured fields are present and their contributing authorities are shown above.
Material change intelligence
View recent updates ↗What changed after publication
No material field changes have been recorded since change tracking began. Routine source refreshes and cosmetic edits are intentionally excluded.
CVE published
Fixed release or patch reference recorded
Technical terms and abbreviations used in this report
- CVE
- Common Vulnerabilities and Exposures: the public identifier for one disclosed vulnerability.
- CVSS
- Common Vulnerability Scoring System: a technical severity framework; it is not patching priority by itself.
- EPSS
- Exploit Prediction Scoring System: FIRST's estimate of the probability that exploitation activity will be observed in the next 30 days; it is a forecast, not confirmation.
- CWE
- Common Weakness Enumeration: the standard category describing the underlying software or hardware weakness.
- CNA
- CVE Numbering Authority: an organisation authorised to assign and publish CVE records.
- CISA ADP
- Cybersecurity and Infrastructure Security Agency Authorized Data Publisher: structured enrichment added to a CVE record.
- NVD
- National Vulnerability Database: NIST's enrichment service for CVE records.
- CERT / CSIRT
- A computer security incident response team that publishes warnings or coordinates incident response.
- PoC
- Proof of concept: public material that demonstrates or helps reproduce exploitation.
- CSAF
- Common Security Advisory Framework: a machine-readable format for security advisories.
- LoTL
- Living off the land: abuse of legitimate tools or system functions during an attack.