The Printer Administration module for Webmin 0.990 and earlier allows remote attackers to execute arbitrary commands via shell metacharacters in the printer name.
The RPC module in Webmin 0.21 through 0.99, when installed without root or admin privileges, allows remote attackers to read and write to arbitrary files and execute arbitrary commands via remote_foreign_require and remote_foreign_call requests.
Webmin 0.84 and earlier does not properly clear the HTTP_AUTHORIZATION environment variable when the web server is restarted, which makes authentication information available to all CGI programs and allows local users to gain privileges.