source: http://www.securityfocus.com/bid/16195/info

Hummingbird Enterprise Collaboration is prone to multiple vulnerabilities.

The following specific issues were identified:

The application reportedly allows remote attackers to upload arbitrary HTML files and script code to the application.

Another vulnerability allows attackers to trick users into downloading potentially malicious files.

An attacker may also disclose sensitive information about the server by sending specially crafted HTTP GET requests.

Hummingbird Enterprise Collaboration 5.2.1 and prior versions are vulnerable to these issues.

To trick users into downloading a potentially malicious file, the file is named 'fake.doc', however, a file with the ID of 1189762 is actually downloaded:
https://www.example.com/hc/hc/fake.doc?d=fc&o=dwnd&fid=1189762&did=89777&x=16080&doc_ext=.txt