"Microsoft is adding a new weapon to its aggressive Windows 10 push—or at least it appears that it is.
[…]
It also appears this ad can’t be stopped by rolling back the update, as it’s built right into KB3139929, a critical security update for IE11.
[…]
Either way, packaging Windows 10 upgrade prompts in a security update is a terrible idea and a breach of user trust." I couldn't agree more!