Hummingbird Collaboration (aka Hummingbird Enterprise Collaboration) 5.21 and earlier allows remote attackers to misrepresent the type and name of a file via modified doc_ext and id parameters, which might trick a user into downloading dangerous or unexpected content.
https://exchange.xforce.ibmcloud.com/vulnerabilities/24068
http://www.vupen.com/english/advisories/2006/0145
http://www.securityfocus.com/archive/1/421392/100/0/threaded