# CVE-2023-36521: Denial of service in SIMATIC MV540 H

> An attacker can cause a denial of service in Siemens SIMATIC MV devices if the result synchronization server is enabled.

- **Severity:** High 8.6 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H/E:P/RL:O/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:** 11 Jul 2023
- **Updated:** 21 Nov 2024
- **Also known as:** GHSA-g2ch-vrrq-vf7w

## What is CVE-2023-36521?

CVE-2023-36521 is a high-severity denial of service vulnerability in Siemens SIMATIC MV540 H, published on 11 Jul 2023. 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 MV540 H (All versions < V3.3.4), SIMATIC MV540 S (All versions < V3.3.4), SIMATIC MV550 H (All versions < V3.3.4), SIMATIC MV550 S (All versions < V3.3.4), SIMATIC MV560 U (All versions < V3.3.4), SIMATIC MV560 X (All versions < V3.3.4). The result synchronization server of the affected products contains a
vulnerability that may lead to a denial of service condition. An attacker may
cause a denial of service situation of all socket-based communication of the
affected products if the result server is enabled.

Weakness: CWE-770 (Allocation of Resources Without Limits or Throttling)

## Which versions are affected by CVE-2023-36521?

It affects 6 products.


Products: Siemens Simatic Mv540 H Firmware, Siemens Simatic Mv540 S Firmware, Siemens Simatic Mv550 H Firmware, Siemens Simatic Mv550 S Firmware, Siemens Simatic Mv560 U Firmware, Siemens Simatic Mv560 X Firmware.

## How do I fix CVE-2023-36521?

No fix has been published for CVE-2023-36521 yet. Limit exposure of the affected software until one is available.

## Is CVE-2023-36521 being exploited?

There is no known exploitation of CVE-2023-36521 in the wild and no public exploit code.

## Other vulnerabilities in Siemens SIMATIC MV540 H

- [CVE-2022-33137](https://insights.sbomify.com/CVE-2022-33137/): Auth bypass in SIMATIC MV540 H (high 8.0)
- [CVE-2023-35920](https://insights.sbomify.com/CVE-2023-35920/): Denial of service in SIMATIC MV540 H (high 7.5)
- [CVE-2023-35921](https://insights.sbomify.com/CVE-2023-35921/): Denial of service in SIMATIC MV540 H (high 7.5)
- [CVE-2022-33138](https://insights.sbomify.com/CVE-2022-33138/): Missing authorization in SIMATIC MV540 H (high 7.5)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2023-36521 and fix it if it is affected.

What it is: CVE-2023-36521 is a high-severity denial of service vulnerability in Siemens SIMATIC MV540 H, published on 11 Jul 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-2023-36521 in the wild and no public exploit code.

Affected product: Siemens SIMATIC MV540 H. 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-2023-36521/ (Markdown: https://insights.sbomify.com/CVE-2023-36521/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2023-36521
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2023-36521
- OSV: https://osv.dev/vulnerability/CVE-2023-36521

---
From sbomify Insights: https://insights.sbomify.com/CVE-2023-36521/
Summaries are generated and may contain mistakes; the official description above is the record.