Buffer overflow in xlssr.dll in the Autonomy KeyView XLS viewer (aka File Viewer for Excel), as used in IBM Lotus Notes 5.x through 8.5.x, Symantec Mail Security, Symantec BrightMail Appliance, Symantec Data Loss Prevention (DLP), and other products, allows remote attackers to execute arbitrary code via a crafted .xls spreadsheet attachment.
http://www.vupen.com/english/advisories/2009/2389
http://www.securityfocus.com/bid/36124
http://www.securityfocus.com/bid/36042
http://www-01.ibm.com/support/docview.wss?uid=swg21396492