dbcve.org
C200 FirmwareOperating system · Honeywell

CVE-2021-38399

HIGH · 7.5 CVSS v3.1 Published 2022-10-28
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
84/100
Remediation priority · High
Remotely reachable No privileges Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
Honeywell Experion PKS C200, C200E, C300, and ACE controllers are vulnerable to relative path traversal, which may allow an attacker access to unauthorized files and directories.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · moderate confidence

This is a relative path traversal vulnerability in Honeywell Experion PKS C200, C200E, C300, and ACE controllers. The flaw allows remote attackers to access unauthorized files and directories on the affected controllers by using relative path sequences (e.g., '../') in crafted requests, potentially exposing sensitive system files, configurations, or credentials.

MitigationApply vendor-supplied patches or firmware updates for the affected controller models. Additionally, implement network segmentation to isolate ICS devices, restrict access to management interfaces via firewall rules, and monitor for suspicious path traversal patterns in network traffic.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
C200 FirmwareOperating system
Affected:all versions
C200e FirmwareOperating system
Affected:all versions
C300 FirmwareOperating system
Affected:all versions
Application Control Environment FirmwareOperating system
Affected:all versions

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
None
Availability
None

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify Honeywell Experion PKS controllers in the environment
    Inventory your network for Honeywell Experion PKS controllers - specifically C200, C200E, C300, or Application Control Environment (ACE) devices. Check your asset management system or perform network scanning for these device types.
    Affected if Any Honeywell C200, C200E, C300, or ACE controller is present in the environment
  2. Determine the firmware version of the controller
    Access the controller's web management interface or use the vendor's diagnostic tools to retrieve the firmware version. Compare this version against the affected ranges.
    Affected if The controller runs any firmware version (all versions of the listed products are affected)
  3. Verify if the management interface is network-accessible
    Check if the controller's web interface or management ports are exposed to the network. Use network scanning to identify open ports on these devices, particularly HTTP/HTTPS ports typically used for web management.
    Affected if The controller's web management interface is accessible from network segments outside the isolated control system network
  4. Review logs for path traversal attempts
    Examine the controller's access logs and security logs for requests containing relative path sequences such as '../', '..\', or unusual file path patterns that may indicate exploitation attempts.
    Affected if Path traversal patterns are found in the logs or network traffic to the controller
  5. Check for unauthorized file access or credential exposure
    Audit system files, configurations, and credential stores on the controller for signs of unauthorized access. Look for unexpected changes to configuration files or access to system directories.
    Affected if Evidence of unauthorized file access or exposure of sensitive configuration files is found

If your environment contains any Honeywell C200, C200E, C300, or ACE controllers with their management interfaces accessible on the network, you are potentially affected by this path traversal vulnerability.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

From vendor data
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Apply vendor-supplied patches or firmware updates for the affected controller models. Additionally, implement network segmentation to isolate ICS devices, restrict access to management interfaces via firewall rules, and monitor for suspicious path traversal patterns in network traffic.

Fix this in C200 Firmware Scoped from the published advisory
  • Consultation12.0 h
  • Implementation16.0 h
  • Testing24.0 h
  • Review / QA8.0 h
60.0 hours of engineering $10,320
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2021-38399 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
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