The Internet Authentication Service (IAS) in Microsoft Windows Vista SP2 and Server 2008 SP2 does not properly validate MS-CHAP v2 Protected Extensible Authentication Protocol (PEAP) authentication requests, which allows remote attackers to execute arbitrary code via crafted structures in a malformed request, aka "Internet Authentication Service Memory Corruption Vulnerability."
https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A6063
https://docs.microsoft.com/en-us/security-updates/securitybulletins/2009/ms09-071