Microsoft is to release 10 fixes for 34 vulnerabilities in its Patch Tuesday monthly security update on 8 June.
According to Microsoft's advance notification, three of the vulnerabilities are "critical" because they can allow an attacker to take full control of the targeted machine, while the remaining seven are ranked as "important".
The critical vulnerabilities affect all Windows versions, including Windows 7 and Internet Explorer 8.
The June release is a large update and will keep system administrators busy, even if they have migrated to Windows 7 already, said Wolfgang Kandek, chief technology officer at security firm Qualys.
The impact will be felt enterprise-wide, with bulletins covering a large portion of Microsoft's range of operating systems and Windows and Office products, said Alan Bentley, vice-president international at security firm Lumension.
"It is strongly suggested that IT administrators plan ahead and prioritise this patch load as soon as possible," he said.
Some of the patches, including one of the critical ones, require a machine reboot after installation, said Kandek.