CVE-2020-6998 Rockwell Automation CompactLogix 5370 and ControlLogix 5570 Controllers Improper Input Validation

Medium 5.8 Published 27 Jul 2022 Updated 17 Apr 2025

Attackers can cause denial of service in Rockwell Automation PLCs by sending crafted CIP packets that trigger an infinite loop during connection establishment.

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-2020-6998?

CVE-2020-6998 is a medium-severity denial of service vulnerability in Rockwell Automation Armor Compact GuardLogix 5370 controllers, published on 27 Jul 2022. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

The connection establishment algorithm found in Rockwell Automation CompactLogix 5370 and ControlLogix 5570 versions 33 and prior does not sufficiently manage its control flow during execution, creating an infinite loop. This may allow an attacker to send specially crafted CIP packet requests to a controller, which may cause denial-of-service conditions in communications with other products.

Weakness: CWE-20

Which versions are affected by CVE-2020-6998?

It affects 9 products.

Products include Rockwellautomation Armor Compact Guardlogix 5370 Firmware, Rockwellautomation Compact Guardlogix 5370 Firmware, Rockwellautomation Compactlogix 5370 L1 Firmware, Rockwellautomation Compactlogix 5370 L2 Firmware, Rockwellautomation Compactlogix 5370 L3 Firmware, Rockwellautomation Controllogix 5570 Firmware and 3 more.

How do I fix CVE-2020-6998?

No fix has been published for CVE-2020-6998 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-2020-6998 being exploited?

There is no known exploitation of CVE-2020-6998 in the wild and no public exploit code.

Sources

Also known as GHSA-9r87-pc5m-9w97.