Sprint LG G Flex 2 LS996 has started receiving Android 5.1.1 Lollipop based Stagefright fix update with build number LS996ZV8. The Stagefright vulnerability is a serious issue which needs to be fixed as soon as possible and that’s the reason in the line of popular devices most of the manufacturer provided their devices with the latest firmware updates with Stagefright bug fix.
The Stagefright fix security update is rolling out via OTA and you will receive the notification anytime soon.Over-The-Air update has some limitation which need to be fulfill by the user to update their devices by this easy method. The rooted devices will not able to receive OTA firmware update as it need a pure stock LG G Flex 2 LS996 for this method to work. If your device is non-rooted give a try to force update check,
Go to Settings >> About device >> Check for System updates.
If the update hits your device you will be notified and the device will ask you to install the updates now or later. The OTA can also take some time to reach your device as things need to be settled up which could take some delay depending on the region where you are using the device but soon it will be available to download in every region.