According to a confirmation by Microsoft late last night, a new zero day vulnerability has been found to affect every version of Internet Explorer. In other words—over a quarter of the entire browser market.

Attacks taking advantage of the vulnerability are largely targeting IE versions 9, 10, and 11 in something called a "use after free" attack. Essentially, the attack corrupts data as soon as memory has been released, most likely after users have been lured to phony websites. Microsoft explains: