Microsoft later confirmed the flaw, and sent out an advisory to users to help mitigate the problem. It is still working on a patch that would solve it.
"The company has determined that Internet Explorer was one of the vectors used in targeted and sophisticated attacks against Google and other corporate networks," Microsoft said.
雖然，微軟CEOChief Executive Officer（執行長）Steve Ballmer接受媒體專訪時，十足避重就輕地，絕口不提IE的安全漏洞。
"We need to take all cyber attacks, not just this one, seriously," said Microsoft Chief Executive Steve Ballmer in an interview on CNBC. "We have a whole team of people that responds in very real time to any report that it may have something to do with our software, which we don't know yet."
The warning from the Federal Office for Information Security comes after Microsoft admitted IE was the weak link in recent attacks on Google's systems.
Microsoft rejected the warning, saying that the risk to users was low and that the browsers' increased security setting would prevent any serious risk.
However, German authorities say that even this would not make IE fully safe.