Microsoft .NET Framework 4 does not properly allocate buffers, which allows remote attackers to execute arbitrary code via (1) a crafted XAML browser application (aka XBAP) or (2) a crafted .NET Framework application, aka ".NET Framework Buffer Allocation Vulnerability."
https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A14655
https://docs.microsoft.com/en-us/security-updates/securitybulletins/2012/ms12-034