Today Apple release a new security update for OS X’s Network Time Protocol service. Apple recommends users with Yosemite, Mavericks, and Mountain Lion install the update as soon as possible. There is no official word on what exactly the update covers. When you go to Apple’s page for more information you are met with this update:
For the protection of our customers, Apple does not disclose, discuss or confirm security issues until a full investigation has occurred and any necessary patches or releases are available.
According to MacRumours the update apparently addresses a security issue announced by the U.S. government on December 19. The issue, originally discovered by Google’s Security Team, gives attackers the potential to execute arbitrary code using ntpd privileges.