CVE-2021-22743

Improper Check for Unusual or Exceptional Conditions vulnerability exists in Triconex TCM 4351B installed on Tricon V11.3.x systems that could cause module reset when TCM receives malformed TriStation packets while the write-protect keyswitch is in the program position.

Published: 2021-05-26 Last update: 2026-06-16 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2021-22743 is rated Low Risk (20.3/100): CVSS Low severity, with low exploitation likelihood (EPSS 0.22%). Monitor for updates and reassess as exploit intelligence or EPSS changes.

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-2021-22743

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 0.06% 0.22% +0.17%
2 2025-03-25 0.05% 0.06% +0.01%
3 2023-03-07 — 0.05% —

Full EPSS history (7 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2021-22743

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
3.9 3.1 LOW
CVSS:3.1/AV:P/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H Click to expand
Attack vector (AV:P)
Hands-on access—USB, keyboard, opening the case—not something you do purely over the wire.
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:H)
They need powerful rights—admin, root, or similar—before this pays off.
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:N)
Data isn’t meaningfully altered or forged.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 0.3 3.6 [email protected]
2.1 2.0 LOW
AV:L/AC:L/Au:N/C:N/I:N/A:P Click to expand
Access vector (AV:L)
Requires local access to the target system.
Access complexity (AC:L)
Exploitation conditions are straightforward and predictable.
Authentication (AU:N)
No authentication is required.
Confidentiality impact (C:N)
No confidentiality impact.
Integrity impact (I:N)
No integrity impact.
Availability impact (A:P)
Partial availability impact.
 3.9 2.9 [email protected]

Weakness enumeration for CVE-2021-22743

Affected software / configurations for CVE-2021-22743

Vendor Product Version Raw CPE
schneider-electric triconex_model_3009_mp_firmware >= 11.3.0, < 11.8.0 cpe:2.3:o:schneider-electric:triconex_model_3009_mp_firmware:*:*:*:*:*:*:*:*
schneider-electric tcm_4351b_firmware >= 11.3.0, < 11.5.1 cpe:2.3:o:schneider-electric:tcm_4351b_firmware:*:*:*:*:*:*:*:*
schneider-electric tcm_4351b_firmware 11.7.0 cpe:2.3:o:schneider-electric:tcm_4351b_firmware:11.7.0:*:*:*:*:*:*:*

References for CVE-2021-22743

cvelogic Threat Intelligence