Windows 2000, XP, and Server 2003 does not properly "validate the use of memory regions" for COM structured storage files, which allows attackers to execute arbitrary code, aka the "COM Structured Storage Vulnerability."
https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A901
https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A2892
https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A2351
https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A1159
https://exchange.xforce.ibmcloud.com/vulnerabilities/19105
https://docs.microsoft.com/en-us/security-updates/securitybulletins/2005/ms05-012
http://www.us-cert.gov/cas/techalerts/TA05-039A.html
http://www.kb.cert.org/vuls/id/597889