Apple iCal 3.0.1 on Mac OS X allows remote CalDAV servers, and user-assisted remote attackers, to cause a denial of service (NULL pointer dereference and application crash) or possibly execute arbitrary code via a .ics file containing (1) a large 16-bit integer on a TRIGGER line, or (2) a large integer in a COUNT field on an RRULE line.
https://exchange.xforce.ibmcloud.com/vulnerabilities/42569
http://www.vupen.com/english/advisories/2008/1601
http://www.securitytracker.com/id?1020094
http://www.securityfocus.com/bid/28629
http://www.securityfocus.com/archive/1/492682/100/0/threaded
http://www.securityfocus.com/archive/1/492638/100/100/threaded
http://www.securityfocus.com/archive/1/492414/100/0/threaded