The patches will include a critical fix for Internet Explorer as well as a related Visual Studio patch rated "moderate" urgency by Microsoft.

"The Internet Explorer bulletin will provide defense-in-depth changes to Internet Explorer to help provide additional protections for the issues addressed by the Visual Studio bulletin," Microsoft said in a late Friday.

The patches are set to be released on Tuesday at 10:00 a.m. West coast time.

Microsoft didn't say exactly what it was fixing. The company typically doesn't rush out these "out-of-band" emergency updates unless the bug is being exploited by cyber criminals; however, in this case the flaws being patched are not being leveraged in attacks, according to Microsoft.

The problem appears to lie in a widely used Windows component called the Active Template Library (ATL). to security researcher Halvar Flake, this flaw is also to blame for an ActiveX bug that Microsoft identified earlier this month. Microsoft issued a kill-bit patch for the problem on July 14, but after looking into the bug, Flake determined that the patch didn't fix the underlying vulnerability, so new attacks are possible.