# CVE-2021-20600: Denial of service in Mitsubishi Electric MELSEC iQ-R series C Controller Module R12CCPU-V

> Remote unauthenticated attackers can cause a denial-of-service condition on Mitsubishi MELSEC iQ-R controllers by flooding packets during startup.

- **Severity:** Medium 5.9 (`CVSS:3.1/AV:N/AC:H/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:** 8 Oct 2021
- **Updated:** 3 Aug 2024
- **Also known as:** GHSA-8r87-v86x-7qm3

## What is CVE-2021-20600?

CVE-2021-20600 is a medium-severity denial of service vulnerability in Mitsubishi Electric MELSEC iQ-R series C Controller Module R12CCPU-V, published on 8 Oct 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Uncontrolled resource consumption in Mitsubishi Electric MELSEC iQ-R series C Controller Module R12CCPU-V Firmware Versions "16" and prior allows a remote unauthenticated attacker to cause a denial-of-service (DoS) condition by sending a large number of packets in a short time while the module starting up. System reset is required for recovery.

Weakness: CWE-400 (Uncontrolled Resource Consumption)

## Which versions are affected by CVE-2021-20600?

It affects 1 product.


Products: Mitsubishielectric R12ccpu-v Firmware.

## How do I fix CVE-2021-20600?

No fix has been published for CVE-2021-20600 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-20600 being exploited?

There is no known exploitation of CVE-2021-20600 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-20600 and fix it if it is affected.

What it is: CVE-2021-20600 is a medium-severity denial of service vulnerability in Mitsubishi Electric MELSEC iQ-R series C Controller Module R12CCPU-V, published on 8 Oct 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-2021-20600 in the wild and no public exploit code.

Affected product: Mitsubishi Electric MELSEC iQ-R series C Controller Module R12CCPU-V. 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-2021-20600/ (Markdown: https://insights.sbomify.com/CVE-2021-20600/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-20600
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-20600
- OSV: https://osv.dev/vulnerability/CVE-2021-20600

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From sbomify Insights: https://insights.sbomify.com/CVE-2021-20600/
Summaries are generated and may contain mistakes; the official description above is the record.