When it comes to security updates, once a month is usually pretty outstanding. Especially when it comes to comparing Nexus or unlocked devices to carrier-locked devices. But Google is getting ready to push out yet another security update for March to the Nexus line up. There is a new critical Linux kernel exploit that was discovered, so Google is patching it as quickly as they can and pre-paring a mid-month update to fix this exploit.
Google did know about this exploit and it was going to be patched in the April 2016 update, but after it was made public by Zimperium and they were able to demonstrate rooting a Nexus 5 and Nexus 6 with an app, Google felt that they needed to fix this exploit ASAP. Google has not named the rooting app that was able to do this, and that's likely a good thing, and to protect users. The patch has already been sent over to AOSP and Android partners and we should begin seeing the OTA roll out to Nexus devices very soon. As for their partners like Samsung, HTC and Motorola, we'll likely see the patch roll out in the April update, especially for the carrier locked devices.
Is this something users should be worried about? Not really. Remember, Google has many ways of checking apps before they are installed on your device. Whether you sideload them or download from the Play Store, Google is always checking to make sure that the apps you are downloading are safe. While it is a bit scary to see this type of exploit available, there are a few things you can do. First of all, you can stick to downloading apps from the Play Store - which we highly suggest anyways. Another is to update your apps and firmware when prompted. A number of users will get an OTA, but not update their phone because they don't want to spend the time doing it (or whatever the reason may be). That can be detrimental to you and your device. So when there is an update, it's best to let it install. If you have to be without your phone for 5 or 10 minutes, it's still totally worth it.
No word on when exactly this new OTA will be available or when the factory images will be available. But they should be rather soon. Looking at the Android Developers site where all of the factory images are located, the latest is the first March build. So they are not yet available.