Microsoft plans on Tuesday to release an emergency fix for a zero-day vulnerability affecting Internet Explorer versions 6 and 7, the software giant announced Monday.

The out-of-band patch will resolve the bug, which was disclosed earlier this month on the same day Microsoft released its March security updates. The vulnerability currently is being exploited in targeted attacks but the issue is not present in IE 8, the newest browser version.

“We recommend that customers install the update as soon as it is available,” Jerry Bryant, group manager of response communications at Microsoft, said in a blog post on Monday.

As users await the fix, the vulnerability can be mitigated through IE Protected Mode, which is turned on by default in IE 7 running on Vista. In addition, Microsoft is offering an automated workaround to mitigate the flaw. This “Fix It” solution mitigates the flaw “by disabling the peer factory class through the modification of a registry key,” the company said.

Releasing an out-of-cycle patch is rare but not unheard of for Microsoft, especially with the company’s next scheduled patch release not until April 13.

In January, Microsoft closed another IE hole, which was leveraged in the Google-China attacks, with an emergency fix.

Tuesday’s patch is expected to arrive at 1 p.m. EST.