Polycom ViewStation before 7.2.4 has a default null password for the administrator account, which allows arbitrary users to conduct unauthorized activities.
http://www.securityfocus.com/bid/5631
http://www.polycom.com/common/pw_item_show_doc/0%2C%2C1444%2C00.pdf
http://www.iss.net/security_center/static/9347.php
http://www.ciac.org/ciac/bulletins/m-123.shtml
http://bvlive01.iss.net/issEn/delivery/xforce/alertdetail.jsp?oid=21089