Microsoft said it was investigating the flaw and suggested a patch may soon be available.
"At the completion of this investigation, Microsoft will take the appropriate action to help protect our customers, which may include providing additional mitigation guidance through this Security Advisory," said the company in a statement.
Most existing versions of Internet Explorer are vulnerable to the exploit and Microsoft has advised users to change security settings in the Internet security zone to high, which sends prompts before running ActiveX controls.
"We have not been made aware of any attacks attempting to use the reported vulnerability or customer impact at this time, but we are aggressively investigating the public report," Microsoft said.
Last week, The U.S. Computer Emergency Readiness Team (US-CERT) issued an alert about a flaw in a Veritas Software data backup product, which it says was being actively exploited.