Microsoft on Wednesday issued an urgent patch to fix an Internet Explorer (IE) web browser flaw that may have been used by hackers to attack millions of computer users.

The security update for IE, dubbed MS08-078, resolves a publicly disclosed vulnerability that "could allow remote code execution if a user views a specially crafted Web page using Internet Explorer," the software giant said in a statement.

The flaw could allow hackers to take control of computers and steal passwords and credit card information.

Writing in a company blog, Mike Reavey, director of the Microsoft Security Response Center, urged users to test and deploy the security update "as quickly as possible."

Microsoft said the update is for IE on all currently supported versions of Windows. Users can now download it for their home computers or laptops from Microsoft Update website.

Microsoft security experts estimated earlier that roughly 0.2 percent of IE users worldwide may have been exposed to websites containing exploits of the latest vulnerability, which means millions of users are in danger of having their computers infected.

Latest statistics from research firm Net Applications showed that IE still dominates the browser market with a share of nearly 70 percent.