One of the updates is for the yet to be released Windows 7
Microsoft will issue its biggest ever security update on 13 October.
The update will include 13 bulletins that between them tackle 34 vulnerabilities.
Microsoft said that eight of the bulletins were rated as critical - the most serious sort of vulnerability.
The security patches will close loopholes in many different programs including different editions of Windows, Internet Explorer and some elements of Office.
One update, rated as critical, tackles a loophole in Internet Explorer 8 running under Windows 7. The next version of Microsoft's operating system is due to be released on 22 October.
Most people will get the updates automatically but links to download them can also be found on Microsoft's security pages. Once applied to a PC, the machine will need to be re-started before the fixes take effect.
In a blog posting giving an outline of the updates, Jerry Bryant, a Microsoft security expert, said two of the fixes were for problems flagged up in earlier advisories.
One of those loopholes, for the File Transfer Protocol (FTP) bundled in with Microsoft's Internet Information Server, is already being exploited by some hi-tech criminals.
Windows is by far the most popular target for cyber criminals and the vast majority of the millions of malicious programs, including worms and trojans, are aimed at the operating system.
Prior to the bumper October security update, Microsoft's biggest ever update was released in June 2009. That package of 10 fixes tackled 31 vulnerabilities.
Microsoft typically issues its updates on the second Tuesday of every month. It started this regular monthly update system in late 2003.