# CVE-2020-28393: Denial of service in SCALANCE XM-400, XR-500

> Unauthenticated attackers can cause permanent denial of service on Siemens SCALANCE switches via crafted OSPF packets if OSPF is enabled.

- **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:** 12 May 2021
- **Updated:** 4 Aug 2024
- **Also known as:** GHSA-q5c9-w6w2-m4fw

## What is CVE-2020-28393?

CVE-2020-28393 is a high-severity denial of service vulnerability in SCALANCE XM-400, XR-500, published on 12 May 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

An unauthenticated remote attacker could create a permanent denial-of-service condition by sending specially crafted OSPF packets. Successful exploitation requires OSPF to be enabled on an affected device on the SCALANCE XM-400, XR-500 (All versions prior to v6.4).

Weakness: CWE-682 (Incorrect Calculation)

## Which versions are affected by CVE-2020-28393?

It affects 11 products.


Products: Siemens Scalance Xm-400 Firmware, Siemens Scalance Xm408-4c Firmware, Siemens Scalance Xm408-4c L3 Firmware, Siemens Scalance Xm408-8c Firmware, Siemens Scalance Xm408-8c L3 Firmware, Siemens Scalance Xm416-4c Firmware, Siemens Scalance Xm416-4c L3 Firmware, Siemens Scalance Xr524 Firmware, Siemens Scalance Xr526 Firmware, Siemens Scalance Xr528 Firmware, Siemens Scalance Xr552 Firmware.

## How do I fix CVE-2020-28393?

No fix has been published for CVE-2020-28393 yet. Limit exposure of the affected software until one is available.

## Is CVE-2020-28393 being exploited?

There is no known exploitation of CVE-2020-28393 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2020-28393 and fix it if it is affected.

What it is: CVE-2020-28393 is a high-severity denial of service vulnerability in SCALANCE XM-400, XR-500, published on 12 May 2021. 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-2020-28393 in the wild and no public exploit code.

Affected product: SCALANCE XM-400, XR-500. 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-2020-28393/ (Markdown: https://insights.sbomify.com/CVE-2020-28393/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2020-28393
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-28393
- OSV: https://osv.dev/vulnerability/CVE-2020-28393

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From sbomify Insights: https://insights.sbomify.com/CVE-2020-28393/
Summaries are generated and may contain mistakes; the official description above is the record.