# CVE-2023-38744: Denial of service in CJ2H CPU Unit

> Remote unauthenticated attackers can cause denial of service in OMRON CJ/CS series PLCs by sending specially crafted packets to the EtherNet/IP port.

- **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 3 Aug 2023
- **Updated:** 17 Oct 2024
- **Also known as:** GHSA-8262-vqgw-h22m

## What is CVE-2023-38744?

CVE-2023-38744 is a high-severity denial of service vulnerability in OMRON Corporation CJ2H CPU Unit, published on 3 Aug 2023. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Denial-of-service (DoS) vulnerability due to improper validation of specified type of input issue exists in the built-in EtherNet/IP port of the CJ Series CJ2 CPU unit and the communication function of the CS/CJ Series EtherNet/IP unit. If an affected product receives a packet which is specially crafted by a remote unauthenticated attacker, the unit of the affected product may fall into a denial-of-service (DoS) condition. Affected products/versions are as follows: CJ2M CPU Unit CJ2M-CPU3[] Unit version of the built-in EtherNet/IP section Ver. 2.18 and earlier, CJ2H CPU Unit CJ2H-CPU6[]-EIP Unit version of the built-in EtherNet/IP section Ver. 3.04 and earlier, CS/CJ Series EtherNet/IP Unit CS1W-EIP21 V3.04 and earlier, and CS/CJ Series EtherNet/IP Unit CJ1W-EIP21 V3.04 and earlier.

Weakness: CWE-1284 (Improper Validation of Specified Quantity in Input)

## Which versions are affected by CVE-2023-38744?

It affects 12 products.


Products: Omron Cj1w-Eip21 Firmware, Omron Cj2h-Cpu64-Eip Firmware, Omron Cj2h-Cpu65-Eip Firmware, Omron Cj2h-Cpu66-Eip Firmware, Omron Cj2h-Cpu67-Eip Firmware, Omron Cj2h-Cpu68-Eip Firmware, Omron Cj2m-Cpu31 Firmware, Omron Cj2m-Cpu32 Firmware, Omron Cj2m-Cpu33 Firmware, Omron Cj2m-Cpu34 Firmware, Omron Cj2m-Cpu35 Firmware, Omron Cs1w-Eip21 Firmware.

## How do I fix CVE-2023-38744?

No fix has been published for CVE-2023-38744 yet. Limit exposure of the affected software until one is available.

## Is CVE-2023-38744 being exploited?

There is no known exploitation of CVE-2023-38744 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2023-38744 and fix it if it is affected.

What it is: CVE-2023-38744 is a high-severity denial of service vulnerability in OMRON Corporation CJ2H CPU Unit, published on 3 Aug 2023. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2023-38744 in the wild and no public exploit code.

Affected product: OMRON Corporation CJ2H CPU Unit. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2023-38744/ (Markdown: https://insights.sbomify.com/CVE-2023-38744/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2023-38744
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2023-38744
- OSV: https://osv.dev/vulnerability/CVE-2023-38744

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From sbomify Insights: https://insights.sbomify.com/CVE-2023-38744/
Summaries are generated and may contain mistakes; the official description above is the record.