CVE-2023-38744Network attack vector

Unauthenticated service interrupt via malformed EtherNet/IP packet

Published Aug 3, 2023 · Updated Oct 17, 2024

Improper input validation in OMRON CJ2 CPU and CS/CJ EtherNet/IP units allows remote attackers to cause a service interrupt. The built-in EtherNet/IP port and communication function process a malformed packet without adequately validating its input type; OMRON has not disclosed the malformed field or parser operation. No authentication or user interaction is required, and successful exploitation puts the PLC or communications unit into a denial-of-service state.

CVSS severity7.5
High
EPSS probability0.87%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper input validation in OMRON CJ2 CPU and CS/CJ EtherNet/IP units allows remote attackers to cause a service interrupt. The built-in EtherNet/IP port and communication function process a malformed packet without adequately validating its input type; OMRON has not disclosed the malformed field or parser operation. No authentication or user interaction is required, and successful exploitation puts the PLC or communications unit into a denial-of-service state.

The record

CVE
CVE-2023-38744
Published
Aug 3, 2023
Updated
Oct 17, 2024
Vendor
OMRON Corporation
Product
CJ2H CPU Units
Classifications
CWE-1287, CWE-1284, T0814
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 3, 2023CVE publishedPublication date reported by the CVE source.
  2. Oct 17, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

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

  1. Affected versionversion=CJ2H-CPU6[]-EIP Unit version of the built-in EtherNet/IP section Ver. 3.04 and earlier

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

OMRON Corporation · CJ2H CPU Unitsversion=CJ2H-CPU6[]-EIP Unit version of the built-in EtherNet/IP section Ver. 3.04 and earlier
OMRON Corporation · CS/CJ Series EtherNet/IP Unitsversion=CJ1W-EIP21 V3.04 and earlier; version=CS1W-EIP21 V3.04 and earlier
OMRON Corporation · CJ2H CPU Unitversion=0 <3.04
OMRON Corporation · CJ2M CPU Unitsversion=CJ2M-CPU3[] Unit version of the built-in EtherNet/IP section Ver. 2.18 and earlier
OMRON Corporation · CJ2M CPU Unitversion=0 <2.18

Published CVSS scores

7.5JPCERT/CCCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
7.5OMRON CorporationCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

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)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-1287Improper Validation of Specified Type of Input
CWE-1284Improper Validation of Specified Quantity in Input
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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