Sony Mobile is pushing a firmware update to the Xperia XA1 Ultra today that moves the build number from 42.0.A.4.153 to version 42.0.A.4.167. The new update adds the 5 January 2018 Android security patches, but little else has changed. The Android version remains Android 7.0 Nougat. If you have updated please post your impressions in the comments below, along with any screenshots of the new firmware.
Thanks walaspancha!