CVE intelligence and bounded remediation

CVE-2021-38395 — Honeywell C200 Firmware security vulnerability

Critical CVSS 9.8

Honeywell Experion PKS C200, C200E, C300, and ACE controllers are vulnerable to improper neutralization of special elements in output, which may allow an attacker to remotely execute arbitrary code and cause a denial-of-service condition.

Severity
Critical
CVSS
9.8 (3.1)
Published
2022-10-28
CISA KEV
Not currently listed
Ecosystem
operating-system
Weaknesses
CWE-74

Affected products

  • honeywell / c200_firmware
  • honeywell / c200e_firmware
  • honeywell / c300_firmware
  • honeywell / application_control_environment_firmware

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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