The Federal Office for Information Security (BSI) issued the warning on Monday evening, saying that users of the browser who have computers on the Windows XP and Windows 7 operating system were particularly at risk.
Some attacks have already been registered, but the BSI said the attack code was, “freely available on the internet so that one should reckon with widespread abuse.”
The Internet Explorer 7 and 8 versions used on Windows XP as well as the Explorer 8 and 9 used with Windows 7 have the security problem, the office said in a statement.
All it takes is for the user to be drawn to a special website, via which the hacker can get into the user's computers.
Microsoft has not yet produced a security update, the BSI said, recommending all Internet Explorer users to use an alternative browser until this happens.