Microsoft published a new security advisory for Excel

Microsoft is investigating new public reports of a vulnerability in Microsoft Office Excel 2003 Service Pack 2, Microsoft Office Excel Viewer 2003, Microsoft Office Excel 2002, Microsoft Office Excel 2000, and Microsoft Excel 2004 for Mac. At this time, our initial investigation indicates that customers who are using Microsoft Office Excel 2007 or Microsoft Excel 2008 for Mac, or who have installed Microsoft Office Excel 2003 Service Pack 3 are not affected by this vulnerability.

Microsoft is investigating the public reports and customer impact. Upon completion of this investigation, Microsoft will take the appropriate action to help protect our customers. This may include providing a security update through our monthly release process or providing an out-of-cycle security update, depending on customer needs.

At this time, we are aware only of targeted attacks that attempt to use this vulnerability. Additionally, as the issue has not been publicly disclosed broadly, we believe the risk at this time to be limited.

Vulnerability in Microsoft Excel Could Allow Remote Code Execution