Improvements and fixes
This security update includes quality improvements. No new operating system features are being introduced in this update. Key changes include:
- Security updates to Windows SMB Server, Windows Kernel, Windows Datacenter Networking, and Windows Graphics.
For more information about the resolved security vulnerabilities, see the Security Update Guide.
Known issues in this update
When calling CoInitializeSecurity, the call will fail if passing RPC_C_IMP_LEVEL_NONE under certain conditions.
When calling CoInitializeSecurity, the call may fail when passing RPC_C_AUTHN_LEVEL_NONE as the authentication level. The error returned on failure is STATUS_BAD_IMPERSONATION_LEVEL.
This issue is resolved in KB4057402.