# CVE-2023-51440: Denial of service in SIMATIC CP 343-1

> Unauthenticated remote attackers can cause denial of service by injecting spoofed TCP RST packets due to improper TCP sequence number validation.

- **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H/E:P/RL:T/RC:C`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 13 Feb 2024
- **Updated:** 2 Aug 2024
- **Also known as:** GHSA-j4h9-5vj5-4vff

## What is CVE-2023-51440?

CVE-2023-51440 is a high-severity denial of service vulnerability in Siemens SIMATIC CP 343-1, published on 13 Feb 2024. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

A vulnerability has been identified in SIMATIC CP 343-1 (6GK7343-1EX30-0XE0) (All versions), SIMATIC CP 343-1 Lean (6GK7343-1CX10-0XE0) (All versions), SIPLUS NET CP 343-1 (6AG1343-1EX30-7XE0) (All versions), SIPLUS NET CP 343-1 Lean (6AG1343-1CX10-2XE0) (All versions). Affected products incorrectly validate TCP sequence numbers. This could allow an unauthenticated remote attacker to create a denial of service condition by injecting spoofed TCP RST packets.

Weakness: CWE-940 (Improper Verification of Source of a Communication Channel)

## Which versions are affected by CVE-2023-51440?

It affects 4 products.


Products: Siemens Simatic Cp 343-1 Firmware, Siemens Simatic Cp 343-1 Lean Firmware, Siemens Siplus Net Cp 343-1 Firmware, Siemens Siplus Net Cp 343-1 Lean Firmware.

## How do I fix CVE-2023-51440?

No fix has been published for CVE-2023-51440 yet. Limit exposure of the affected software until one is available.

## Is CVE-2023-51440 being exploited?

There is no known exploitation of CVE-2023-51440 in the wild and no public exploit code.

## Other vulnerabilities in Siemens SIMATIC CP 343-1

- [CVE-2015-8214](https://insights.sbomify.com/CVE-2015-8214/): Missing authorization in n/a (critical 9.7)
- [CVE-2016-8673](https://insights.sbomify.com/CVE-2016-8673/): Cross-site request forgery in n/a (high 8.8)
- [CVE-2018-4843](https://insights.sbomify.com/CVE-2018-4843/): Other in SIMATIC CP 343-1 (incl. SIPLUS variants) (medium 6.5)
- [CVE-2016-8672](https://insights.sbomify.com/CVE-2016-8672/): Information disclosure in n/a (medium 5.3)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2023-51440 and fix it if it is affected.

What it is: CVE-2023-51440 is a high-severity denial of service vulnerability in Siemens SIMATIC CP 343-1, published on 13 Feb 2024. 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-2023-51440 in the wild and no public exploit code.

Affected product: Siemens SIMATIC CP 343-1. 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-2023-51440/ (Markdown: https://insights.sbomify.com/CVE-2023-51440/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2023-51440
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2023-51440
- OSV: https://osv.dev/vulnerability/CVE-2023-51440

---
From sbomify Insights: https://insights.sbomify.com/CVE-2023-51440/
Summaries are generated and may contain mistakes; the official description above is the record.