source: http://www.securityfocus.com/bid/34150/info

Sun Java System Calendar Server is prone to a denial-of-service vulnerability because it fails to handle certain duplicate URI requests.

An attacker can exploit this issue to crash the Calendar Server, resulting in a denial-of-service condition.

NOTE: Versions prior to Sun Java System Calendar Server 6.3 are not vulnerable. 

The following example data is available:

https://www.example.com:3443/?tzid=crash