Recently Microsoft had released one security patch KB3021952 and installation of this KB on Windows 7 box is causing issues in our WPF hosted application. If same KB is installed on any other OS then we dont face any issue. When we uninstall this KB from Win 7 box then our application starts working fine.

In the application we have CustomSecurityManagerEx2 implemented from WebBrowser.WebBrowserSite, IServiceProviderEx2 and IInternetSecurityManagerEx2 interfaces.

In this, when IServiceProvider.QueryService is called, it tries to create ppvObject object by type casting this object to IInternetSecurityManagerEx2. Here this is of type CustomSecurityManagerEx2. As part of this it tried to execute all methods of IInternetSecurityManagerEx2 interface but as soon as it goes to call the first method GetSecurityIdEx2, there itself this.m_WebBrowser.Document throws the exception of type UnauthorizedAccesssException.

Not sure what is causing this break with the latest KB on Win 7. Please give me some idea on this issue.