The Windows XP source code was allegedly leaked online

[atom0s]

Not sure why you guys think nothing in XP is still being used in 10. There is no reason for Microsoft to rewrite everything from scratch every edition or even for a major edition such as 10 outside of the main core and specific libraries that directly require it. I wouldn't be surprised if we see a lot of news popping up in the near future regarding various new 0days, patches from Microsoft to fix known problems that are now going to be mainstream that were ignored for the time being, etc. with this being a public thing now.