CVE-2018-7790 Auth bypass in Modicon M221, all references, all versions prior to firmware V1.6.2.0

Critical 9.8 Published 29 Aug 2018 Updated 29 May 2026

Attackers can replay authentication sequences to bypass security and upload the original program from the PLC.

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-2018-7790?

CVE-2018-7790 is a critical authentication bypass 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 Information Management Error 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 replay authentication sequences. If an attacker exploits this vulnerability and connects to a Modicon M221, the attacker can upload the original program from the PLC.

Weakness: CWE-294

Which versions are affected by CVE-2018-7790?

It affects 1 product.

Products include Schneider-Electric Modicon M221 Firmware.

How do I fix CVE-2018-7790?

No fix has been published for CVE-2018-7790 yet. Limit exposure of the affected software until one is available.

Upgrade, and rotate credentials and sessions that may have been exposed. More about Authentication bypass.

Is CVE-2018-7790 being exploited?

There is no known exploitation of CVE-2018-7790 in the wild and no public exploit code.

Sources

Also known as GHSA-xvmg-mf7x-g2hx.