https://www.bleepingcomputer.com/news/security/microsoft-rolls-out-new-intel-microcode-for-windows-10-server-2016/

Microsoft has released multiple microcode updates that mitigate additional variants of the speculative code execution vulnerabilities affecting Intel processors. The patches cover the recently disclosed CPU flaws generically referred to as Foreshadow or L1 Terminal Fault.

All security gaps covered by these patches are varieties of the Spectre vulnerability revealed on the first days of the year. It affects all microprocessors that use branch prediction and speculative code execution to increase performance. In plain terms, the CPU tries to guess the destination of the code and runs it in memory.