Unspecified vulnerability in Microsoft Excel 2004 and earlier, and Microsoft Office Excel Viewer 2003, allows remote attackers to execute arbitrary code via an Excel file with a malformed header, which triggers memory corruption. NOTE: due to lack of details from the vendor, it is not clear whether this is the same issue as CVE-2007-3490.

More... (http://nvd.nist.gov/nvd.cfm?cvename=CVE-2008-0081)