CVE-2021-20612 Denial of service in MELSEC-F series FX3U-ENET; MELSEC-F series FX3U-ENET-L; MELSEC-F series FX3U-ENET-P502

High 7.5 Published 14 Jan 2022 Updated 3 Aug 2024

Remote unauthenticated attackers can cause a denial-of-service condition in Mitsubishi MELSEC-F series PLC communication modules by sending crafted packets.

Exploited in the wild: Not known
Login needed: Not needed
Attackable: Over the internet
Victim action needed: Not needed
Fix: None listed

What is CVE-2021-20612?

CVE-2021-20612 is a high-severity denial of service vulnerability in MELSEC-F series FX3U-ENET; MELSEC-F series FX3U-ENET-L; MELSEC-F series FX3U-ENET-P502, published on 14 Jan 2022. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

Lack of administrator control over security vulnerability in MELSEC-F series FX3U-ENET Firmware version 1.14 and prior, FX3U-ENET-L Firmware version 1.14 and prior and FX3U-ENET-P502 Firmware version 1.14 and prior allows a remote unauthenticated attacker to cause a denial-of-service (DoS) condition in communication function of the product or other unspecified effects by sending specially crafted packets to an unnecessary opening of TCP port. Control by MELSEC-F series PLC is not affected by this vulnerability, but system reset is required for recovery.

Which versions are affected by CVE-2021-20612?

It affects 3 products.

Products include Mitsubishielectric Fx3u-Enet-L Firmware, Mitsubishielectric Fx3u-Enet-P502 Firmware, Mitsubishielectric Fx3u-Enet Firmware.

How do I fix CVE-2021-20612?

No fix has been published for CVE-2021-20612 yet. Limit exposure of the affected software until one is available.

Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.

Is CVE-2021-20612 being exploited?

There is no known exploitation of CVE-2021-20612 in the wild and no public exploit code.

Sources

Also known as GHSA-v6rf-w7jv-9fmc.