Microsoft Excel 2000 SP3 through 2003 SP2, Viewer 2003, Compatibility Pack, and Office 2004 and 2008 for Mac allows user-assisted remote attackers to execute arbitrary code via malformed tags in rich text, aka "Excel Rich Text Validation Vulnerability."
https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A5212
https://docs.microsoft.com/en-us/security-updates/securitybulletins/2008/ms08-014
http://www.vupen.com/english/advisories/2008/0846/references
http://www.us-cert.gov/cas/techalerts/TA08-071A.html
http://www.securitytracker.com/id?1019586
http://www.securityfocus.com/bid/28168
http://www.securityfocus.com/archive/1/489430/100/0/threaded