Microsoft Excel 2002 SP3, 2003 SP3, 2007 SP2, and 2010; Office 2004, 2008, and 2011 for Mac; Open XML File Format Converter for Mac; and Excel Viewer SP2 do not properly handle errors during the parsing of Office Art records in Excel spreadsheets, which allows remote attackers to execute arbitrary code via a malformed object record, related to a "stray reference," aka "Excel Linked List Corruption Vulnerability."
https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A12595
https://docs.microsoft.com/en-us/security-updates/securitybulletins/2011/ms11-021
http://zerodayinitiative.com/advisories/ZDI-11-041/
http://www.vupen.com/english/advisories/2011/0940
http://www.us-cert.gov/cas/techalerts/TA11-102A.html
http://www.securitytracker.com/id?1025337
http://secunia.com/advisories/43231
http://secunia.com/advisories/39122
http://dvlabs.tippingpoint.com/blog/2011/02/07/zdi-disclosure-microsoft