Microsoft Excel 2007 SP3, Office Compatibility Pack SP3, and Excel Viewer allow remote attackers to execute arbitrary code via a crafted Office document, aka "Microsoft Office Memory Corruption Vulnerability."
https://euvd.enisa.europa.eu/vulnerability/EUVD-2015-6120
https://docs.microsoft.com/en-us/security-updates/securitybulletins/2015/ms15-131