QUOTE
Attack code for a new security hole in Excel has surfaced on the Internet, just as Microsoft is scrambling to respond to a separate bug in the spreadsheet program.
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Security monitoring company Secunia deems the issue "highly critical," one notch below its most severe ranking
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More at http://news.zdnet.com/2100-1009_22-6085982.html

Also Microsoft have published an advisor on the first Excel vulnerability, see http://www.microsoft.com/technet/security/...ory/921365.mspx