CVE-2018-7789 Denial of service in Modicon M221, all references, all versions prior to firmware V1.6.2.0

Medium 4.8 Published 29 Aug 2018 Updated 29 May 2026

Unauthorized users can remotely reboot Schneider Electric Modicon M221 PLCs via crafted protocol frames, causing service disruption.

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-2018-7789?

CVE-2018-7789 is a medium-severity denial of service vulnerability in Schneider Electric SE Modicon M221, all references, all versions prior to firmware V1.6.2.0, published on 29 Aug 2018. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

An Improper Check for Unusual or Exceptional Conditions vulnerability exists in Schneider Electric's Modicon M221 product (all references, all versions prior to firmware V1.6.2.0). The vulnerability allows unauthorized users to remotely reboot Modicon M221 using crafted programing protocol frames.

Weakness: CWE-754

Which versions are affected by CVE-2018-7789?

It affects 1 product.

Products include Schneider-Electric Modicon M221 Firmware.

How do I fix CVE-2018-7789?

No fix has been published for CVE-2018-7789 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-2018-7789 being exploited?

There is no known exploitation of CVE-2018-7789 in the wild and no public exploit code.

Sources

Also known as GHSA-mw2w-h237-7rhw.