CVE-2021-22743

Module reboot via malformed TriStation packet handling

Published May 26, 2021 · Updated Aug 3, 2024

Denial of service in Schneider Electric Triconex TCM 4351B on Tricon 11.3.x allows attackers to reset the module via malformed TriStation packets. The TCM firmware fails to handle unusual conditions in malformed TriStation packets and resets the communication module. Access to the write-protect keyswitch and its program position is required, so the consequence is a module reboot rather than data access or modification.

CVSS severity3.9
Low
EPSS probability0.22%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Denial of service in Schneider Electric Triconex TCM 4351B on Tricon 11.3.x allows attackers to reset the module via malformed TriStation packets. The TCM firmware fails to handle unusual conditions in malformed TriStation packets and resets the communication module. Access to the write-protect keyswitch and its program position is required, so the consequence is a module reboot rather than data access or modification.

The record

CVE
CVE-2021-22743
Published
May 26, 2021
Updated
Aug 3, 2024
Vendor
Schneider Electric
Product
Triconex TCM 4351B
Classifications
CWE-754, T0814
Attack vector
physical
Privileges
admin

Timeline

How it unfolded

  1. May 26, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=Triconex TCM 4351B installed on Tricon V11.3.x systems

What conditions does exploitation require?

Attack vectorphysical
Required privilegesadmin

What is affected?

Schneider Electric · Triconex TCM 4351Bversion=Triconex TCM 4351B installed on Tricon V11.3.x systems

Published CVSS scores

3.9NIST NVDCVSS:3.1/AV:P/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H
2.1NIST NVDAV:L/AC:L/Au:N/C:N/I:N/A:P

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorphysical
Privilegesadmin
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-754Improper Check for Unusual or Exceptional Conditions
T0814Denial of Service

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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