Microsoft Excel 2002 SP3; Office 2004, 2008, and 2011 for Mac; and Open XML File Format Converter for Mac do not properly validate record information during parsing of Excel spreadsheets, which allows remote attackers to execute arbitrary code or cause a denial of service (memory corruption) via a crafted spreadsheet, aka "Excel Memory Heap Overwrite Vulnerability."
https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A12736
https://docs.microsoft.com/en-us/security-updates/securitybulletins/2011/ms11-045