# CVE-2020-5527: Denial of service in MELSOFT transmission port (UDP/IP) of multiple Mitsubishi Electric MELSEC series

> Attackers can cause denial of service in Mitsubishi Electric MELSEC PLCs by sending massive data to the MELSOFT transmission port, disrupting industrial operations.

- **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:** 30 Mar 2020
- **Updated:** 4 Aug 2024
- **Also known as:** GHSA-5jq2-477f-97vj

## What is CVE-2020-5527?

CVE-2020-5527 is a high-severity denial of service vulnerability in MELSOFT transmission port (UDP/IP) of multiple Mitsubishi Electric MELSEC series, published on 30 Mar 2020. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

When MELSOFT transmission port (UDP/IP) of Mitsubishi Electric MELSEC iQ-R series (all versions), MELSEC iQ-F series (all versions), MELSEC Q series (all versions), MELSEC L series (all versions), and MELSEC F series (all versions) receives massive amount of data via unspecified vectors, resource consumption occurs and the port does not process the data properly. As a result, it may fall into a denial-of-service (DoS) condition. The vendor states this vulnerability only affects Ethernet communication functions.

Weakness: CWE-400 (Uncontrolled Resource Consumption)

## Which versions are affected by CVE-2020-5527?

It affects 46 products.


Products: Mitsubishielectric Cr800-Q Firmware, Mitsubishielectric Fx3g Firmware, Mitsubishielectric Fx3gc Firmware, Mitsubishielectric Fx3s Firmware, Mitsubishielectric Fx3u Firmware, Mitsubishielectric Fx3uc Firmware, Mitsubishielectric Fx5u Firmware, Mitsubishielectric Fx5uc Firmware, Mitsubishielectric Fx5uj Firmware, Mitsubishielectric L02cpu-P Firmware, Mitsubishielectric L02cpu Firmware, Mitsubishielectric L02scpu-P Firmware, Mitsubishielectric L02scpu Firmware, Mitsubishielectric L06cpu-P Firmware, Mitsubishielectric L06cpu Firmware, Mitsubishielectric L26cpu-Bt Firmware, Mitsubishielectric L26cpu-P Firmware, Mitsubishielectric L26cpu-Pbt Firmware, Mitsubishielectric L26cpu Firmware, Mitsubishielectric Q02phcpu Firmware and 26 more.

## How do I fix CVE-2020-5527?

No fix has been published for CVE-2020-5527 yet. Limit exposure of the affected software until one is available.

## Is CVE-2020-5527 being exploited?

There is no known exploitation of CVE-2020-5527 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2020-5527 and fix it if it is affected.

What it is: CVE-2020-5527 is a high-severity denial of service vulnerability in MELSOFT transmission port (UDP/IP) of multiple Mitsubishi Electric MELSEC series, published on 30 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-2020-5527 in the wild and no public exploit code.

Affected product: MELSOFT transmission port (UDP/IP) of multiple Mitsubishi Electric MELSEC series. 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-2020-5527/ (Markdown: https://insights.sbomify.com/CVE-2020-5527/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2020-5527
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-5527
- OSV: https://osv.dev/vulnerability/CVE-2020-5527

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From sbomify Insights: https://insights.sbomify.com/CVE-2020-5527/
Summaries are generated and may contain mistakes; the official description above is the record.