CVE-2021-38395 | Honeywell Experion PKS and ACE Controllers Injection

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.

Published: 2022-10-27 Last update: 2026-06-17 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2021-38395 is rated Moderate Risk (55.8/100): CVSS Critical severity, with medium exploitation likelihood (EPSS 0.87%). Review affected assets and schedule remediation.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2021-38395

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-15 0.39% 0.87% +0.48%
2 2025-11-21 0.75% 0.39% -0.35%
3 2025-11-18 — 0.75% —

Full EPSS history (14 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2021-38395

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
9.1 3.1 CRITICAL
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 5.2 [email protected]
9.8 3.1 CRITICAL
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 5.9 [email protected]

Weakness enumeration for CVE-2021-38395

Affected software / configurations for CVE-2021-38395

Vendor Product Version Raw CPE
honeywell c200_firmware — cpe:2.3:o:honeywell:c200_firmware:-:*:*:*:*:*:*:*
honeywell c200e_firmware — cpe:2.3:o:honeywell:c200e_firmware:-:*:*:*:*:*:*:*
honeywell c300_firmware — cpe:2.3:o:honeywell:c300_firmware:-:*:*:*:*:*:*:*
honeywell application_control_environment_firmware — cpe:2.3:o:honeywell:application_control_environment_firmware:-:*:*:*:*:*:*:*

References for CVE-2021-38395

cvelogic Threat Intelligence