CVE intelligence and bounded remediation

CVE-2021-32706 — Pi-hole's Web interface provides a central location to manage a Pi-hole instance and review performance statistics

High CVSS 8.8

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 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.

Severity
High
CVSS
8.8 (3.1)
Published
2021-08-04
CISA KEV
Not currently listed
Ecosystem
software/application
Weaknesses
CWE-94

Affected products

  • pi-hole / pi-hole

Matched remediation archetype

Command, code, expression, and template injection

This catalog composition supplies bounded fallback guidance. Explicitly reviewed curated workflows load with the complete record below.

Check exposure

  • Trace untrusted values to process execution, interpreters, evaluators, template engines, dynamic imports, and administrative scripting features.
  • Determine whether the affected path is reachable across each trust boundary and which service account or host privilege it inherits.
  • Review configuration for optional execution features, unsafe compatibility modes, and shell invocation.

Remediate safely

  • Replace string-built commands or evaluated code with fixed operations and structured argument APIs that do not invoke a shell.
  • Use strict allowlists for operation identifiers and reject unexpected input before it reaches any interpreter.
  • Update the affected component and add inert regression tests covering metacharacters, encoding variants, and alternate request paths.

Authoritative sources

Complete CVE record and remediation plan

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