The server for 53KF Web IM 2009 Home, Professional, and Enterprise editions relies on client-side protection mechanisms against cross-site scripting (XSS), which allows remote attackers to conduct XSS attacks by using a modified client to send a crafted IM message, related to the msg variable.
https://exchange.xforce.ibmcloud.com/vulnerabilities/48096
http://www.securityfocus.com/bid/33341
http://www.securityfocus.com/archive/1/500169/100/0/threaded