This indicates an attack attempt to exploit a Memory Corruption vulnerability in Apple QuickTime.
The vulnerability is due to insufficient validation when parsing a malformed file. A remote attacker may be able to exploit this to execute arbitrary code within the context of the application, via a maliciously crafted file.
Apple Computer Quicktime prior to 188.8.131.52.95
System Compromise: Remote attackers can gain control of vulnerable systems.
Apply the most recent upgrade or patch from the vendor.