CGI implementation in Yaws web server versions 1.81 to 2.0.7 is vulnerable to OS command injection.
https://www.debian.org/security/2020/dsa-4773
https://vuln.be/post/yaws-xxe-and-shell-injections/
https://usn.ubuntu.com/4569-1/
https://packetstormsecurity.com/files/159106/Yaws-2.0.7-XML-Injection-Command-Injection.html
https://lists.debian.org/debian-lts-announce/2020/09/msg00022.html