Mitsubishi Electric Co.’s MELSEC iQ-F Series FX5-ENET/IP Ethernet Module

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Summary

Successful exploitation of this vulnerability could allow a remote attacker to cause a denial-of-service (DoS) condition in the affected product by continuously sending a large number of communication packets to the Ethernet port of the product in a short period of time, increasing the processing load of the product, preventing the internal anomaly-detection processing from being performed, and causing the communication function to stop.

The following versions of Mitsubishi Electric Co.’s MELSEC iQ-F Series FX5-ENET/IP Ethernet Module are affected:

• Mitsubishi Electric MELSEC iQ-F Series FX5-ENET/IP Ethernet Module FX5-ENET/IP vers:all/* (CVE-2026-8806)

Background

• Critical Infrastructure Sectors: Critical Manufacturing
• Countries/Areas Deployed: Worldwide
• Company Headquarters Location: Japan

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Vulnerabilities

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Acknowledgments

• Mitsubishi Electric discovering this vulnerability

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Legal Notice and Terms of Use

This product is provided subject to this Notification (https://www.cisa.gov/notification) and this Privacy & Use policy (https://www.cisa.gov/privacy-policy).

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Recommended Practices

CISA recommends users take defensive measures to minimize the exploitation risk of these vulnerabilities.

Minimize network exposure for all control system devices and/or systems, and ensure they are not accessible from the internet.

Locate control system networks and remote devices behind firewalls and isolate them from business networks.

When remote access is required, use more secure methods, such as Virtual Private Networks (VPNs), recognizing VPNs may have vulnerabilities and should be updated to the most recent version available. Also recognize VPN is only as secure as its connected devices.

CISA reminds organizations to perform proper impact analysis and risk assessment prior to deploying defensive measures.

CISA also provides a section for control systems security recommended practices on the ICS webpage on cisa.gov. Several CISA products detailing cyber defense best practices are available for reading and download, including Improving Industrial Control Systems Cybersecurity with Defense-in-Depth Strategies.

CISA encourages organizations to implement recommended cybersecurity strategies for proactive defense of ICS assets. Additional mitigation guidance and recommended practices are publicly available on the ICS webpage at cisa.gov in the technical information paper, ICS-TIP-12-146-01B–Targeted Cyber Intrusion Detection and Mitigation Strategies.

Organizations observing suspected malicious activity should follow established internal procedures and report findings to CISA for tracking and correlation against other incidents.

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Advisory Conversion Disclaimer

This ICSA is a verbatim republication of Mitsubishi Electric 2026-003 from a direct conversion of the vendor’s Common Security Advisory Framework (CSAF) advisory. This is republished to CISA’s website as a means of increasing visibility and is provided “as-is” for informational purposes only. CISA is not responsible for the editorial or technical accuracy of republished advisories and provides no warranties of any kind regarding any information contained within this advisory. Further, CISA does not endorse any commercial product or service. Please contact Mitsubishi Electric directly for any questions regarding this advisory.

Revision History

• Initial Release Date: 2026-06-18

Date	Revision	Summary
2026-06-18	1	Initial Publication
2026-06-18	2	Initial CISA Republication of Mitsubishi Electric 2026-003 advisory

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Legal Notice and Terms of Use