In Webmin through 1.910, any user authorized to the "Package Updates" module can execute arbitrary commands with root privileges via the data parameter to update.cgi.
https://www.exploit-db.com/exploits/46984
https://pentest.com.tr/exploits/Webmin-1910-Package-Updates-Remote-Command-Execution.html
http://www.securityfocus.com/bid/108790
http://packetstormsecurity.com/files/153372/Webmin-1.910-Remote-Command-Execution.html