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 0.92, when installed from an RPM, creates /var/webmin with insecure permissions (world readable), which could allow local users to read the root user's cookie-based authentication credentials and possibly hijack the root user's session using the credentials.
The web interface for Webmin 0.92 does not properly quote or filter script code in files that are displayed to the interface, which allows local users to execute script and possibly steal cookies by inserting the script into certain files or fields, such as a real user name entry in the passwd file.
Cross-site scripting vulnerability in the authentication page for (1) Webmin 0.96 and (2) Usermin 0.90 allows remote attackers to insert script into an error page and possibly steal cookies.
(1) Webmin 0.96 and (2) Usermin 0.90 with password timeouts enabled allow local and possibly remote attackers to bypass authentication and gain privileges via certain control characters in the authentication information, which can force Webmin or Usermin to accept arbitrary username/session ID combinations.