Microsoft has announced that Intel has completed software validations and have started to release new microcode for current CPU platforms that will protect users against two Spectre variants and L1TF.
The first Spectre variant is called Rogue System Register Read and the second one is Speculative Store Bypass. For those unaware, L1TF stands for L1 Terminal Fault.
As Microsoft noted, this update is a standalone update that is targeted at Windows 10, version 1809 (Windows 10 October 2018 Update) and Windows Server 2019. This update also includes Intel microcode updates that were already released for these operating systems at the time of release to manufacturing (RTM).
Those interested can download the microcode security update from here. This link also lists the CPUs for which this new update can be used (basically all CPUs from the 6th generation and up).