Microsoft Exchange 2000 Server SP3, Exchange Server 2003 SP2, and Exchange Server 2007 SP1 do not properly interpret Transport Neutral Encapsulation (TNEF) properties, which allows remote attackers to execute arbitrary code via a crafted TNEF message, aka "Memory Corruption Vulnerability."
https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A6114
https://docs.microsoft.com/en-us/security-updates/securitybulletins/2009/ms09-003
http://www.us-cert.gov/cas/techalerts/TA09-041A.html