A group of developers managed to find a method for rooting the Galaxy Note 8 variant powered by the Qualcomm Snapdragon 835 SoC without tripping Samsung's Knox protection and have detailed their findings on the boards of XDA Developers. The technique is called SamFAIL, with its name being indicative of some ommissions on the South Korean original equipment manufacturer's part in regards to preventing the Galaxy Note 8 from being rooted. While many of Samsung's previous high-end models proved to be relatively difficult to root and the indie dev scene took months to crack them, the Galaxy Note 8 seemingly isn't one of them, at least as far as the SM-N950U model is concerned, and the same should hold true for other variants of the phablet sporting Qualcomm's premium silicon.
The technique itself will require you to flash a modified system image containing a custom boot image using Samsung's own ODIN tool. Given how the actual software is getting installed on the device using the company's first-party program, reversing the process is as easy as just flashing a stock image from Samsung and since the method doesn't trip Knox, it also won't void your warranty. On the downside, SafetyNet will still be broken by flashing the image and seeing how obtaining root requires a secure boot image in the first place, you won't be able to get Magisk on the device which prevents you from restoring SafetyNet and using services like Android Pay. Finally, the rooted Galaxy Note 8 will only be able to charge to 80 percent running the modified system image for unknown reasons which are likely related to battery safety. Samsung Pay also won't work following the rooting process due to the two security switches it utilizes, though flashing the stock image back will restore its functionality.
The technique itself also won't unlock your bootloader and is relatively straightforward, albeit time-consuming; refer to the banner below for a step-by-step guide on how to utilize SamFAIL. Following this breakthrough, a more stable rooting method with fewer caveats is to be expected in the near future, though it remains to be seen how long the indie dev scene takes to come up with it.