A significant flaw, at the core of the Internet, could let hackers take control of the Web, without users being aware of it.
Software and hardware vendors have been working in secret to fix the flaw for months and, on Tuesday, released a patch.
The flaw is in the way computers are routed to Web page addresses and could be exploited by hackers to route Internet uses to "phishing" sites, regardless of the address they typed into the browser.
The flaw was discovered about six months ago by security researcher Dan Kaminsky about six months ago. He alerted IT industry players to its existence and they have been collaborating on finding a solution.
Users can go to Kaminsky's Web page, www.doxpara.com, to find out if their computers are vulnerable.