CVE-2021-20591: Mitsubishielectric r00cpu Firmware

High severity, CVSS 7.5. EPSS: 1.5% chance of exploitation in the next 30 days.

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.

Affected products

• Mitsubishielectric r00cpu Firmware: any version
• Mitsubishielectric r01cpu Firmware: any version
• Mitsubishielectric r02cpu Firmware: any version
• Mitsubishielectric r04cpu Firmware: any version
• Mitsubishielectric r08cpu Firmware: any version
• Mitsubishielectric r08pcpu Firmware: any version
• Mitsubishielectric r08psfcpu Firmware: any version
• Mitsubishielectric r08sfcpu Firmware: any version
• Mitsubishielectric r120cpu Firmware: any version
• Mitsubishielectric r120pcpu Firmware: any version
• Mitsubishielectric r120psfcpu Firmware: any version
• Mitsubishielectric r120sfcpu Firmware: any version
• Mitsubishielectric r16cpu Firmware: any version
• Mitsubishielectric r16pcpu Firmware: any version
• Mitsubishielectric r16psfcpu Firmware: any version
• Mitsubishielectric r16sfcpu Firmware: any version
• Mitsubishielectric r32cpu Firmware: any version
• Mitsubishielectric r32pcpu Firmware: any version
• Mitsubishielectric r32psfcpu Firmware: any version
• Mitsubishielectric r32sfcpu Firmware: any version

Published 2021-06-11. Last modified 2026-06-17.