# CVE-2025-8531: Integer overflow in MELSEC-Q Series Q03UDVCPU

> Remote attackers can cause denial of service in Mitsubishi MELSEC-Q PLCs via integer underflow when user authentication is enabled.

- **Severity:** Medium 6.8 (`CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/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:** 19 Sep 2025
- **Updated:** 24 Sep 2025
- **Also known as:** GHSA-r7hp-8xqq-gfpr

## What is CVE-2025-8531?

CVE-2025-8531 is a medium-severity vulnerability in Mitsubishi Electric Corporation MELSEC-Q Series Q03UDVCPU, published on 19 Sep 2025. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Improper Handling of Length Parameter Inconsistency vulnerability in Mitsubishi Electric Corporation MELSEC-Q Series Q03UDVCPU, Q04UDVCPU, Q06UDVCPU, Q13UDVCPU, Q26UDVCPU, Q04UDPVCPU, Q06UDPVCPU, Q13UDPVCPU, and Q26UDPVCPU with the first 5 digits of serial No. "24082" to "27081" allows a remote attacker to cause an integer underflow by sending specially crafted packets to the affected product to stop Ethernet communication and the execution of control programs on the product, when the user authentication function is enabled. The user authentication function is enabled by default only when settings are configured by GX Works2, which complies with the Cybersecurity Law of the People's Republic of China, and is normally disabled.

Weakness: CWE-130 (Improper Handling of Length Parameter Inconsistency)

## Which versions are affected by CVE-2025-8531?


## How do I fix CVE-2025-8531?

No fix has been published for CVE-2025-8531 yet. Limit exposure of the affected software until one is available.

## Is CVE-2025-8531 being exploited?

There is no known exploitation of CVE-2025-8531 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2025-8531 and fix it if it is affected.

What it is: CVE-2025-8531 is a medium-severity vulnerability in Mitsubishi Electric Corporation MELSEC-Q Series Q03UDVCPU, published on 19 Sep 2025. 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-2025-8531 in the wild and no public exploit code.

Affected product: Mitsubishi Electric Corporation MELSEC-Q Series Q03UDVCPU. 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-2025-8531/ (Markdown: https://insights.sbomify.com/CVE-2025-8531/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-8531
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-8531
- OSV: https://osv.dev/vulnerability/CVE-2025-8531

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From sbomify Insights: https://insights.sbomify.com/CVE-2025-8531/
Summaries are generated and may contain mistakes; the official description above is the record.