CVE-2021-38395Network attack vector

Remote code execution via undisclosed output injection

Published Oct 28, 2022 · Updated Apr 16, 2025

Output injection in Honeywell Experion PKS C200, C200E, C300, and ACE controllers allows remote attackers to execute code or crash controllers. The public CNA and vendor materials identify improper neutralization of special elements in output but do not disclose the affected interface, parser, or unsafe output operation. Unauthenticated network reachability is sufficient, and successful exploitation changes controller behavior or interrupts controlled processes without reported data disclosure.

CVSS severity9.1
Critical
EPSS probability0.94%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Output injection in Honeywell Experion PKS C200, C200E, C300, and ACE controllers allows remote attackers to execute code or crash controllers. The public CNA and vendor materials identify improper neutralization of special elements in output but do not disclose the affected interface, parser, or unsafe output operation. Unauthenticated network reachability is sufficient, and successful exploitation changes controller behavior or interrupts controlled processes without reported data disclosure.

The record

CVE
CVE-2021-38395
Published
Oct 28, 2022
Updated
Apr 16, 2025
Vendor
Honeywell Technologies
Product
Experion PKS
Classifications
CWE-74, T0866
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

9.1ICS-CERTCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H

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-74Improper Neutralization of Special Elements in Output Used by a Downstream Component ('Injection')
T0866Exploitation of Remote Services

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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