Lenovo sub-brand ZUK has started rolling out a new update to its Z2 smartphone. The update brings latest security patch - post-update, the Android security patch level will be October 1. The update also includes several other improvements such as those related to camera and volume. Given that the update has just started rolling out, it may take time for the update notification to pop up on your device's screen. Meanwhile, if you feel impatient, you can manually check for the update by heading to your handset's Settings menu. Via
Source: http://www.gsmarena.com/october_security_update_starts_hitting_zuk_z2-news-21236.php