CVE-2020-5665: Mitsubishielectric Melsec Iq-F FX5U CPU Firmware

High severity, CVSS 7.4. EPSS: 1% chance of exploitation in the next 30 days.

Improper check or handling of exceptional conditions in MELSEC iQ-F series FX5U(C) CPU unit firmware version 1.060 and earlier allows an attacker to cause a denial-of-service (DoS) condition on program execution and communication by sending a specially crafted ARP packet.

Affected products

• Mitsubishielectric Melsec Iq-F FX5U CPU Firmware: up to and including 1.060

Published 2020-12-14. Last modified 2026-06-17.