A new software update (6.0.1) have been release to Moto X G2
It need to be download via WiFi network
After the update:
The security patch level become 1-May-2016 (Before update it is 1-Nov-2015 only)
Moto X (2nd Generation) - Release Notes
Before the update, the phone on 1-Nov-2015 security patch level which is hit all (4) Quadrooter vulnerability
After this update, the phone hit 1 only...
Hopefully, Lenovo will release Sep 2016 security patch very soon to fix the remaining one vulnerability.