A CWE-755: Improper Handling of Exceptional Conditions vulnerability exists in Modicon M580, Modicon M340, Modicon BMxCRA and 140CRA modules (all firmware versions), which could cause a Denial of Service attack on the PLC when upgrading the firmware with a missing web server image inside the package using FTP protocol.
https://www.se.com/ww/en/download/document/SEVD-2019-281-02/