Secunia Security Advisory – David Maciejak has discovered a weakness in WebCalendar, which can be exploited by malicious people to identify valid user accounts.
You can download this advisory from the following link: https://packetstormsecurity.com/files/download/46068/sa19974.txt
Source: https://packetstormsecurity.com/files/46068/Secunia-Security-Advisory-19974.html