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Fencer Intel
high 7.5

CVE-2021-38399 json

Honeywell Experion PKS and ACE Controllers Relative Path Traversal

published 4y ago modified 4mo ago also EUVD-2021-24851

cvss
7.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.9%
EPSS 0.9% chance of exploitation in 30 days, percentile 60%
public exploits
0
none known

Summary

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.

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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 7.5

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

0.93% chance of exploitation in the next 30 days, higher than 60% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by version score vector
CNA 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
NVD 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

Affected products

  • Honeywell Experion PKS

Classification

Weakness
  • CWE-23 Relative Path Traversal
  • CWE-22 Improper Limitation of a Pathname to a Restricted Directory

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.