Microsoft on Tuesday will release an emergency patch for a weakness hackers are exploiting in earlier versions of its Internet Explorer (IE) Web browser software.
"We recommend that customers install the update as soon as it is available," the US software titan said in a message posted Monday at its security response center website.
"We have been monitoring this issue and have determined an out-of-band release is needed to protect customers."
Microsoft routinely releases software patches the second Tuesday of each month and only resorts to "out-of-band" fixes when it deems it too dangerous to wait.
Early in March, Microsoft said it was investigating a hole that cyber attackers are taking advantage of in IE 6 and IE 7.
Hackers could use the flaw to remotely seize control of computers. The new IE 8 Web browser and an old IE 5 version are not affected, according to the US software giant.
The warning came less than two months after Microsoft released a patch for an IE 6 software hole through which China-based cyber spies attacked Google and other firms.
No matter which Web browser people use, upgrading to the most current version promises to increase protection against hackers.
Nine other software patches, some for IE 8, will be released Tuesday along with the high-priority fix, according to Microsoft.Reuse content