CVE-2021-38399Network attack vector

Unauthorized file read via relative path traversal

Published Oct 28, 2022 · Updated Apr 16, 2025

Relative path traversal in Honeywell Experion PKS C200, C200E, C300, and ACE controllers allows remote attackers to read unauthorized files. Honeywell and CISA have not published the affected interface or the pathname-processing operation that fails to confine relative paths. Network reachability without authentication is sufficient, and the reported consequence is limited to file disclosure rather than modification or service interruption.

CVSS severity7.5
High
EPSS probability0.79%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Relative path traversal in Honeywell Experion PKS C200, C200E, C300, and ACE controllers allows remote attackers to read unauthorized files. Honeywell and CISA have not published the affected interface or the pathname-processing operation that fails to confine relative paths. Network reachability without authentication is sufficient, and the reported consequence is limited to file disclosure rather than modification or service interruption.

The record

CVE
CVE-2021-38399
Published
Oct 28, 2022
Updated
Apr 16, 2025
Vendor
Honeywell Technologies
Product
Experion PKS
Classifications
CWE-23
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Oct 28, 2022CVE publishedPublication date reported by the CVE source.
  2. Apr 16, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=ACE controllers
  2. Affected versionversion=C200
  3. Affected versionversion=C200E
  4. Affected versionversion=C300

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Honeywell Technologies · Experion PKSversion=ACE controllers; version=C200; version=C200E; version=C300

Published CVSS scores

7.5NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
7.5ICS-CERTCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-23Relative Path Traversal

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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