CGIscript.net csMailto.cgi program allows remote attackers to use csMailto as a "spam proxy" and send mail to arbitrary users via modified (1) form-to, (2) form-from, and (3) form-results parameters.
http://www.cgiscript.net/cgi-script/csNews/csNews.cgi?database=cgi.db&command=viewone&id=5