Mozilla isn't the only one grappling with a serious web browser security flaw. Microsoft has confirmed to TechCrunch that it will fix an Internet Explorer security exploit already being used for "limited targeted attacks." The vulnerability lets attackers corrupt memory used for the scripting engine in IE9, IE10 and IE11 in a way that would let the intruder run arbitrary code with the same permissions as the user, letting them hijack a PC. It's believed to be similar to the Firefox issue disclosed a week earlier.