https://arstechnica.com/gadgets/2018/01/new-windows-patch-disables-intels-bad-spectre-microcode-fix/

Microsoft has released a new Windows patch to disable Intel's hardware-based mitigation for the Spectre attack due to bugs introduced by Intel's mitigation.

In the wake of the Spectre and Meltdown attacks that use the speculative execution behavior of modern processors to leak sensitive information, Intel released a microcode update that offers operating systems additional controls over the processor's ability to predict branches. When paired with corresponding operating system changes, the extra controls can prevent the unwanted information disclosure.