Canonical has released a new Linux Intel microcode update for Ubuntu that fixes an issue causing Intel Skylake CPUs to hang after a warm reboot. New Intel microcodes were released to mitigate a vulnerability discovered in the Transactional Synchronization Extensions (TSX) feature in Intel processors and a vulnerability in Intel Xeon processors that could lead to a denial of service attack from a local privileged user. Users who to wish to install the new update manually can download them for your respective version of Ubuntu from the links below.
Source: https://www.bleepingcomputer.com/news/linux/ubuntu-linux-gets-intel-microcode-update-to-fix-cpu-hangs/