Microsoft delivered six patches on Tuesday - four critical - as part of its regular Patch Tuesday update cycle.
High on the critical list are patches for Outlook Express and Windows Mail, which cover flaws in the handling of malformed NNTP (Network News Transfer Protocol) responses, and a cumulative update for Internet Explorer 7.
Critical vulnerabilities in Word and Kodak Image Viewer also lend themselves to remote code execution.
All these risks are pretty severe, but some are more severe than others. The Word vulnerability has been abused in targeted exploits, the SANS Institute's Internet Storm Centre reports, and therefore ought to be a higher priority for patching.
Redmond also released two patches that earned the less severe "important" rating. These updates cover a privilege elevation bug in Sharepoint portal software and a denial of service bug in Windows RPC.