The appears to be receiving January security updates ahead of the smartphone going on sale in the U.S. later this month. The 5X isn't expected to hit shelves officially , but at least you'll know said patches will be applied prior to availability.
The update, according to a screenshot over on our forums, totals 111MB, which should bump the handset up to 'January 1 security patch level'.
Do you plan to purchase one on the day of retail release? Let us know in the comments.