CVE intelligence and bounded remediation

CVE-2018-3969 — An exploitable vulnerability exists in the verified boot protection of the CUJO Smart Firewall

High CVSS 8.2

An exploitable vulnerability exists in the verified boot protection of the CUJO Smart Firewall. It is possible to add arbitrary shell commands into the dhcpd.conf file, that persist across reboots and firmware updates, and thus allow for executing unverified commands. To trigger this vulnerability, a local attacker needs to be able to write into /config/dhcpd.conf.

Severity
High
CVSS
8.2 (3.0)
Published
2019-03-21
CISA KEV
Not currently listed
Ecosystem
software/application
Weaknesses
CWE-78

Affected products

  • getcujo / smart_firewall / 7003

Matched remediation archetype

Command, code, expression, and template injection

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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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