# CVE-2019-18336: Denial of service in SIMATIC S7-300 CPU family (incl. related ET200 CPUs and SIPLUS variants)

> Unauthenticated remote attackers can cause Siemens industrial controllers to enter defect mode via crafted Profinet packets, requiring a restart to recover.

- **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:** 10 Mar 2020
- **Updated:** 2 Jun 2026
- **Also known as:** GHSA-q53p-vg4g-3rxp

## What is CVE-2019-18336?

CVE-2019-18336 is a high-severity denial of service vulnerability in Siemens AG SIMATIC S7-300 CPU family (incl. related ET200 CPUs and SIPLUS variants), published on 10 Mar 2020. 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 S7-300 CPU family (incl. related ET200 CPUs and SIPLUS variants) (All versions < V3.X.17), SIMATIC TDC CP51M1 (All versions < V1.1.8), SIMATIC TDC CPU555 (All versions < V1.1.1), SINUMERIK 840D sl (All versions < V4.8.6), SINUMERIK 840D sl (All versions < V4.94). Specially crafted packets sent to port 102/tcp (Profinet) could cause the affected device to go into defect mode. A restart is required in order to recover the system. Successful exploitation requires an attacker to have network access to port 102/tcp, with no authentication. No user interation is required. At the time of advisory publication no public exploitation of this security vulnerability was known.

Weakness: CWE-400 (Uncontrolled Resource Consumption)

## Which versions are affected by CVE-2019-18336?

It affects 12 products.


Products: Siemens Simatic S7-300 Cpu 312 Ifm Firmware, Siemens Simatic S7-300 Cpu 313 Firmware, Siemens Simatic S7-300 Cpu 314 Firmware, Siemens Simatic S7-300 Cpu 314 Ifm Firmware, Siemens Simatic S7-300 Cpu 315-2 Dp Firmware, Siemens Simatic S7-300 Cpu 315 Firmware, Siemens Simatic S7-300 Cpu 316-2 Dp Firmware, Siemens Simatic S7-300 Cpu 318-2 Firmware, Siemens Simatic S7-300 Cpu Firmware, Siemens Simatic Tdc Cp51m1 Firmware, Siemens Simatic Tdc Cpu555 Firmware, Siemens Sinumerik 840d Sl.

## How do I fix CVE-2019-18336?

No fix has been published for CVE-2019-18336 yet. Limit exposure of the affected software until one is available.

## Is CVE-2019-18336 being exploited?

There is no known exploitation of CVE-2019-18336 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2019-18336 and fix it if it is affected.

What it is: CVE-2019-18336 is a high-severity denial of service vulnerability in Siemens AG SIMATIC S7-300 CPU family (incl. related ET200 CPUs and SIPLUS variants), published on 10 Mar 2020. 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-2019-18336 in the wild and no public exploit code.

Affected product: Siemens AG SIMATIC S7-300 CPU family (incl. related ET200 CPUs and SIPLUS variants). 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-2019-18336/ (Markdown: https://insights.sbomify.com/CVE-2019-18336/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2019-18336
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2019-18336
- OSV: https://osv.dev/vulnerability/CVE-2019-18336

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From sbomify Insights: https://insights.sbomify.com/CVE-2019-18336/
Summaries are generated and may contain mistakes; the official description above is the record.