Usermin 0.980 through 1.x before 1.660 allows uconfig_save.cgi sig_file_free remote code execution because it uses the two argument (not three argument) form of Perl open.
Cross-site scripting vulnerability exists in session_login.cgi of Webmin versions prior to 1.970 and Usermin versions prior to 1.820. If this vulnerability is exploited, an arbitrary script may be executed on the web browser of the user who accessed the website using the product. As a result, a webpage may be altered or sensitive information such as a credential may be disclosed.
Cross-site scripting (XSS) vulnerability in Usermin before 1.600 allows remote attackers to inject arbitrary web script or HTML via unspecified vectors. NOTE: this might overlap CVE-2014-3924.
Multiple cross-site scripting (XSS) vulnerabilities in pam_login.cgi in Webmin before 1.350 and Usermin before 1.280 allow remote attackers to inject arbitrary web script or HTML via the (1) cid, (2) message, or (3) question parameter. NOTE: some of these details are obtained from third party information.