Apple Security Advisory 2013-07-02-1 - Security Update 2013-003 is now available and addresses multiple arbitrary code execution vulnerabilities in QuickTime.
c9b13d54d297a2db3d423a575aded10be3fbd77b2ef2e80d714924e848546c51
Apple Security Advisory 2013-05-22-1 - QuickTime 7.7.4 is now available and addresses multiple issues including buffer overflows and arbitrary code execution vulnerabilities.
86bbe08e4962075f0ac3583cedede6a84c05e0fd1931a516233e0cc9267e7b8c