Apple released OS X 10.9.2 on Tuesday, fixing a large security hole unearthed by developers this month, along with improvements to other system features.
The update, rolling out to Mavericks machines now, fixes a serious SSL bug that allowed hackers to gain access to encrypted traffic such as usernames and passwords.
Beyond the Mac, the SSL bug was found to have existed on the iPhone and iPad as well, since iOS 6. Apple released a fix in the form of an iOS 7 update last week.
The 10.9.2 update for the Mac also added the ability to make and receive FaceTime audio calls, rather than just video. This provides Apple with a competitor to Skype across all of its devices - sadly not cross-platform to Android though.
Call waiting for FaceTime, ability to block incoming iMessages from other users, improvements for AutoFill in Safari and a fix for a sound issue on the Mac, were also featured in the 10.9.2 update.