You have probably already heard about the Meltdown and Spectre flaws in the Intel CPUs.  The flaw has existed in the chips since 1995.  This flaw also effects any OS that uses the Intel chips that are effected, so it's not just Windows, this also effects Linux and the MacOS.

To learn more, check out the article I just posted about how to check if your Windows computer is effected, "Meltdown and Spectre CPU Flaws".