# CVE-2020-5668: Denial of service in MELSEC iQ-R

> Remote unauthenticated attackers can cause denial of service in Mitsubishi MELSEC iQ-R modules by sending specially crafted SLMP packets.

- **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:** 20 Nov 2020
- **Updated:** 4 Aug 2024
- **Also known as:** GHSA-9rm6-q34g-q949

## What is CVE-2020-5668?

CVE-2020-5668 is a high-severity denial of service vulnerability in Mitsubishi Electric Corporation MELSEC iQ-R, published on 20 Nov 2020. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Uncontrolled resource consumption vulnerability in MELSEC iQ-R Series modules (R00/01/02CPU firmware version '19' and earlier, R04/08/16/32/120 (EN) CPU firmware version '51' and earlier, R08/16/32/120SFCPU firmware version '22' and earlier, R08/16/32/120PCPU firmware version '25' and earlier, R08/16/32/120PSFCPU firmware version '06' and earlier, RJ71EN71 firmware version '47' and earlier, RJ71GF11-T2 firmware version '47' and earlier, RJ72GF15-T2 firmware version '07' and earlier, RJ71GP21-SX firmware version '47' and earlier, RJ71GP21S-SX firmware version '47' and earlier, and RJ71GN11-T2 firmware version '11' and earlier) allows a remote unauthenticated attacker to cause an error in a CPU unit and cause a denial-of-service (DoS) condition in execution of the program and its communication, or to cause a denial-of-service (DoS) condition in communication via the unit by receiving a specially crafted SLMP packet

Weakness: CWE-400 (Uncontrolled Resource Consumption)

## Which versions are affected by CVE-2020-5668?

It affects 28 products.


Products: Mitsubishielectric R00cpu Firmware, Mitsubishielectric R01cpu Firmware, Mitsubishielectric R02cpu Firmware, Mitsubishielectric R04cpu Firmware, Mitsubishielectric R08cpu Firmware, Mitsubishielectric R08pcpu Firmware, Mitsubishielectric R08psfcpu Firmware, Mitsubishielectric R08sfcpu Firmware, Mitsubishielectric R120cpu Firmware, Mitsubishielectric R120pcpu Firmware, Mitsubishielectric R120psfcpu Firmware, Mitsubishielectric R120sfcpu Firmware, Mitsubishielectric R16cpu Firmware, Mitsubishielectric R16pcpu Firmware, Mitsubishielectric R16psfcpu Firmware, Mitsubishielectric R16sfcpu Firmware, Mitsubishielectric R32cpu Firmware, Mitsubishielectric R32pcpu Firmware, Mitsubishielectric R32psfcpu Firmware, Mitsubishielectric R32sfcpu Firmware and 8 more.

## How do I fix CVE-2020-5668?

No fix has been published for CVE-2020-5668 yet. Limit exposure of the affected software until one is available.

## Is CVE-2020-5668 being exploited?

There is no known exploitation of CVE-2020-5668 in the wild and no public exploit code.

## Other vulnerabilities in Mitsubishi Electric Corporation MELSEC iQ-R

- [CVE-2021-20591](https://insights.sbomify.com/CVE-2021-20591/): Denial of service in MELSEC iQ-R series CPU modules (high 7.5)
- [CVE-2020-16850](https://insights.sbomify.com/CVE-2020-16850/): Denial of service in n/a (high 7.5)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2020-5668 and fix it if it is affected.

What it is: CVE-2020-5668 is a high-severity denial of service vulnerability in Mitsubishi Electric Corporation MELSEC iQ-R, published on 20 Nov 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-2020-5668 in the wild and no public exploit code.

Affected product: Mitsubishi Electric Corporation MELSEC iQ-R. 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-2020-5668/ (Markdown: https://insights.sbomify.com/CVE-2020-5668/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2020-5668
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-5668
- OSV: https://osv.dev/vulnerability/CVE-2020-5668

---
From sbomify Insights: https://insights.sbomify.com/CVE-2020-5668/
Summaries are generated and may contain mistakes; the official description above is the record.