While it has only recently released the Android 4.4.3 update for Nexus devices, Google has now already started to roll out a new Android 4.4.4 update, which might not be as big as the previous one but does take care of some rather important security issue.
According to the changelog leaked by Sprint, the new Android 4.4.4 update brings a patch for the OpenSSL bug, which has similar issues like the Heartbleed bug which was fixed by the Android 4.4.3 update.
The OTA update is currently rolling out to Nexus 5 devices and it should appear on all other Nexus devices, including Nexus 4, Nexus 7 and Nexus 10, pretty soon.
Source:
AndroidPolice.com.