Cyber Resilience

CVE-2021-32706

RCE in Pi-Hole ≤ 5.5.1

Public PoCHigh EPSSRCE
Published
04 August 2021
Modified
21 November 2024
CVSS Score v3.1 7.6
Click a component to see what it means
Raw vectorCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:H
EPSS Score 0.60 99.0th percentile
Risk Priority 80 floored blend · peak EPSS

Summary

CVE-2021-32706 is a high-severity Code Injection (CWE-94) vulnerability in Pi-Hole Pi-Hole. Its CVSS base score is 7.6 (High).

Operationally, ranked in the top 1.0% of CVEs by exploit likelihood; it is not currently listed in the CISA KEV catalog; a public proof-of-concept is referenced.

OWASP Top 10 for Web (2025)

EU & UK References

Vulnerability Data

Pi-hole's Web interface provides a central location to manage a Pi-hole instance and review performance statistics. Prior to Pi-hole Web interface version 5.5.1, the `validDomainWildcard` preg_match filter allows a malicious character through that can be used to execute code, list…

more

directories, and overwrite sensitive files. The issue lies in the fact that one of the periods is not escaped, allowing any character to be used in its place. A patch for this vulnerability was released in version 5.5.1.

CWE(s)

Related Threats

Likely ATT&CK TechniquesAI

Techniques this vulnerability likely enables, inferred from its description, weakness type, and attributed-actor tradecraft. Confidence is per-technique.

T1059 Command and Scripting Interpreter Executionconfidence: HIGH
The preg_match filter flaw allows arbitrary command execution via crafted input.
T1083 File and Directory Discovery Discoveryconfidence: MEDIUM
Directory listing is explicitly mentioned as a possible outcome of the flaw.
inferred from description + CWE · MITRE ATT&CK Enterprise v19.0

CVEs Like This One

CVE-2024-44069Same product: Pi-Hole Pi-Hole
CVE-2020-8816Same product: Pi-Hole Pi-Hole
CVE-2026-33727Same product: Pi-Hole Pi-Hole
CVE-2024-28247Same product: Pi-Hole Pi-Hole
CVE-2024-34361Same product: Pi-Hole Pi-Hole
CVE-2020-11108Same product: Pi-Hole Pi-Hole
CVE-2025-34087Same product: Pi-Hole Pi-Hole
CVE-2026-26952Same vendor: Pi-Hole
CVE-2026-33404Same vendor: Pi-Hole
CVE-2026-33765Same vendor: Pi-Hole

Affected Assets

pi-hole
pi-hole
≤ 5.5.1

Mitigating Controls

Control response

Prevent
Stop it (NIST 800-53)

Detect
Catch it (NIST detect / respond)

Harden
Shrink the surface (DISA STIG)

Validate
Prove the fix (OWASP ASVS)
  • V1.3.1

Likely Mitigating Controls AI

Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.

addresses: CWE-94

Makes persistent code injection into loaded programs impossible when the executable image itself resides on hardware-protected read-only media.

addresses: CWE-94

Dynamically generated code can be produced and executed inside the isolated chamber, preventing host compromise from code-injection payloads.

addresses: CWE-94

Validates inputs used in dynamic code generation to block injected directives.

addresses: CWE-94

Directly prevents execution of attacker-supplied code written into data memory regions.

Mitigating Controls (NIST CSF 2.0) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.

PR.PS-06 mostly match
prevents

PR.PS-06's SDLC practices directly target injection flaws via secure coding and testing (mostly), yet as a single broad outcome it leaves many code-generation specifics unaddressed (partial).

PR.DS-10 none match
prevents

PR.DS-10 protects runtime data confidentiality/integrity but has no bearing on neutralizing externally influenced input during code generation, so neither direction shows any preventive effect.

Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.

prevents

Banning unapproved code samples and unauthenticated web services, combined with secure-coding standards and SAST, prevents the dynamic generation or inclusion of attacker-supplied code.

none

Controls that restrict unauthorized or malicious code from being introduced via external networks or removable media limit opportunities for an attacker to inject and execute arbitrary code.

References