Sony Mobile has updated the firmware for the Xperia XA1 family, which now includes the 5 December 2017 Android security patches. Sony has kept the phones on Android 7.0, so there’s no big Android update just yet.
The Xperia XA1 sees its firmware number move from 40.0.A.6.162 to version 40.0.A.6.175, while the Xperia XA1 Ultra sees its build number from 42.0.A.4.101 to version 42.0.A.4.153. The Xperia XA1 Plus firmware has moved from 48.0.A.1.99 to 48.0.A.1.117.
Thanks Aouadj, Domingo and Mike!