Samsung started updating the international variants of the Galaxy Note 8 with the second August Android security patch earlier this week, having initiated the rollout in the United Kingdom and the United Arab Emirates, though more markets should follow suit by the end of the month. The new firmware is identified by the build number "N950FXXU4CRH3" and comes shortly after the unlocked Exynos versions of the 2017 flagship already started receiving the original security update dated August 1, making it unclear what exactly changed between the two software packages.
The changelog accompanying the patch doesn't mention anything outside of security improvements, though the update likely contains at least one critical bug fix, especially seeing how it initially appeared in countries where the deployment of the original OTA package has already been completed. If Samsung identified minor issues with the previous firmware update, it likely would have packaged them with the September patch, so an earlier release implies more important problems were discovered and waiting wasn't an option that the company deemed good enough. A small subset of owners of the unlocked Exynos 8890 variants of the Galaxy Note 8 claimed the majority of their devices' sensors save for the fingerprint reader stopped functioning following the installation of the first August update, though it's presently unclear whether those issues were resolved with the new software package from Samsung.
Unlocked Galaxy Note 8 models in select territories may still be stuck on the June 2018 patch but should receive the newer firmware version in the coming weeks, together with some variants of the Galaxy S9 and Galaxy S9 Plus powered by the Exynos 9810 chip. The recently announced Galaxy Note 9 is Samsung's first Android smartphone to run the August security patch out of the box, with the handset currently being available for pre-orders around the world and being scheduled for a global release on Friday, August 24.