Microsoft Tuesday patched eight vulnerabilities, all rated critical, in four security updates for Windows, Office, Windows Media Player, Internet Explorer 6, SQL Server and other programs.

Unlike last month, when Microsoft issued 12 bulletins that fixed 26 flaws, today's patched vulnerabilities did not include any that have already been exploited in the wild.

"It doesn't look too bad today," said Andrew Storms, director of security operations at security vendor nCircle Network Security, comparing the count to August's. "Although anything running Windows will have to be updated with MS08-052."

That bulletin, highlighted by Storms and other experts as the one most crucial to patch immediately, fixes a total of five vulnerabilities in the GDI+ component of Windows. GDI+ (Graphics Device Interface) debuted in Windows XP, and is a core part of Windows Vista and the current server-side operating systems, Windows Server 2003 and Windows Server 2008.

"It's one of the foundations for graphic display in Windows," said Storms. "Anyone running XP or newer -- and who isn't these days -- will have to update."

Hackers could exploit the GDI+ bugs by sending specially-crafted image files in a variety of formats -- including EMF, GIF, WMF and BMG -- to a user via e-mail, or by convincing users to visit sites that contain malicious images files. By triggering the vulnerabilities, attackers could then follow up with additional malware to hijack the system or steal data.

"This was the one we were most concerned about last week," said Storms, referring to last Thursday, when Microsoft, as is its practice, posted an advance notice of what it would deliver today. "Then, we predicted that it was going to be a core system or component. And that's essentially what we got."

Symantec researcher Ben Greenbaum echoed Storms' concern over MS08-052. "The vulnerabilities that affect GDI+ are the most dangerous because GDI+ is used in such a large array of Microsoft and third-party software," he said in an e-mail.

There's also the potential that attackers might be able to recycle older code to craft an attack. "At least one of these vulnerabilities is very similar to one that we have seen before," said Greenbaum, "so hackers may be able to use old code or at the very least apply knowledge gained from previous attacks as a starting point for creating new malicious code."