This vulnerability allows remote attackers to execute arbitrary code on vulnerable installations of Apple Mac OSX. Authentication is not required to exploit this vulnerability.
The flaw exists within the libsecurity_cdsa_plugin which implements routines defined in libsecurity_cssm. The library defines an allocation routine as having an argument type uint32. The implemented methods in the cdsa_plugin accept parameter having type size_t, this value is truncated from 64 bits to 32 bits when being passed to the library routine. This can lead to an underallocated memory region and ultimately a write out of bounds. A remote attacker can exploit this vulnerability to execute arbitrary code under the context of the process.