Microsoft Exchange Server 2000 SP3, 2003 SP1 and SP2, and 2007 does not properly decode certain MIME encoded e-mails, which allows remote attackers to execute arbitrary code via a crafted base64-encoded MIME e-mail message.
https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A1890
https://exchange.xforce.ibmcloud.com/vulnerabilities/33889
https://docs.microsoft.com/en-us/security-updates/securitybulletins/2007/ms07-026
http://www.vupen.com/english/advisories/2007/1711
http://www.us-cert.gov/cas/techalerts/TA07-128A.html
http://www.securitytracker.com/id?1018015
http://www.securityfocus.com/bid/23809
http://www.securityfocus.com/archive/1/468871/100/200/threaded
http://www.kb.cert.org/vuls/id/343145