The Snap7 server component in version 1.4.1, when an attacker sends a crafted packet with COTP protocol the last-data-unit flag set to No and S7 writes a var function, the Snap7 server will be crashed.
Source: https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-22552
Reference (s):
- http://snap7.com
- https://sourceforge.net/p/snap7/discussion/bugfix/thread/456d76fdde/
- https://sourceforge.net/projects/snap7/