ExtCalendar version 2.0 Beta 2 suffers from a cross site scripting vulnerability.
You can download this advisory from the following link: https://packetstormsecurity.com/files/download/86762/ZSL-2010-4928.txt
Source: https://packetstormsecurity.com/files/86762/ExtCalendar-2.0-Beta-2-Cross-Site-Scripting.html