In keeping with its usual schedule, Microsoft today released a batch of 17 security bulletins, and associated security patches, for Windows and related software; together, the patches address 32 identified vulnerabilities. Nine of these bulletins have a maximum severity rating of Critical; seven are rated Important. Each supported version of Windows has several Critical vulnerabilities. (For a breakdown of severity ratings by Windows version, see my preview post of last Thursday.) There are also bulletins for Microsoft Office (including Microsoft Office for Mac), Silverlight, Forefront, and Visual Studio. Further details, and download links for the updates, are in the Security Bulletin Summary for June 2011.
Microsoft says that nine of these patches will definitely require a system reboot; the others may require a reboot, depending on the configuration of the patched system. As usual, I recommend that you install these patches as soon as you conveniently can.
The folks at the SANS Internet Storm Center have also posted their usual monthly summary of these bulletins, along with their own severity assessments.