Webmin 1.973 is affected by Cross Site Request Forgery (CSRF) to create a privileged user through Webmin's add users feature, and then get a reverse shell through Webmin's running process feature.
Arbitrary command execution can occur in Webmin through 1.962. Any user authorized for the Package Updates module can execute arbitrary commands with root privileges via vectors involving %0A and %0C. NOTE: this issue exists because of an incomplete fix for CVE-2019-12840.
XSS exists in Webmin 1.941 and earlier affecting the Save function of the Read User Email Module / mailboxes Endpoint when attempting to save HTML emails. This module parses any output without sanitizing SCRIPT elements, as opposed to the View function, which sanitizes the input correctly. A malicious user can send any JavaScript payload into the message body and execute it if the user decides to save that email.
An XSS Vulnerability exists in Webmin 1.941 and earlier affecting the Cluster Shell Commands Endpoint. A user may enter any XSS Payload into the Command field and execute it. Then, after revisiting the Cluster Shell Commands Menu, the XSS Payload will be rendered and executed.