Google have started rolling out a minor system update for the Nexus devices.
This includes the older Nexus 7 tablet from 2012 as well.
The update is barely 1.3 MB in size and fixes some security issues and has a few minor tweaks.
The build number has been changed to JWR66Y.
The earlier update for Android 4.3 was JWR66V.
You can wait for the OTA update for your device or manually download the entire factory image from Google and flash it using a toolkit.
You will have to re-install a custom recovery such as the TWRP (Twam Win Recovery Project) and manually root it by flashing the SuperSU app.
