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Fencer Intel
critical 9.1

CVE-2021-38395 json

Honeywell Experion PKS and ACE Controllers Injection

published 4y ago modified 4mo ago also EUVD-2021-24847

cvss
9.1
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
1.2%
EPSS 1.2% chance of exploitation in 30 days, percentile 67%
public exploits
0
none known

Summary

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.

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Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

cisa ICSA-21-278-04 updated cvss 9.1

Honeywell Experion PKS and ACE Controllers

  • Honeywell C200 Honeywell C200E Honeywell C300 and ACE controllers
    affected: mitigation “Honeywell recommends users follow all guidance in the Experion Network and Security Planning Guide to prevent attacks by malicious actors.” honeywellprocess.com

From CISA ICS and IT advisories (CSAF, https://github.com/cisagov/CSAF), a U.S. Government work; changed: reduced to products, statuses and remediations. CISA notification · csaf

CISA SSVC

Exploitation
none
Automatable
yes
Technical impact
partial
Assessed
last yr.

Exploit prediction

1.15% chance of exploitation in the next 30 days, higher than 67% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by version score vector
CNA 3.1 9.1 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H
NVD 3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Affected products

  • Honeywell Experion PKS

Classification

Weakness
  • CWE-74 Improper Neutralization of Special Elements in Output Used by a Downstream Component

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.