This update includes only security updates. No new operating system features are being introduced in this update. Key changes include:
Security updates to Windows DVD Maker, Microsoft Graphics Component, Windows kernel-mode drivers, Windows Media Player, Microsoft XML Core Services, Windows OS, SHA-1 deprecation for SSL/TLS certificates, Windows kernel, Microsoft Uniscribe, SMB Server, Windows Hyper-V, Internet Information Services, and Active Directory Federation Services.
For a complete list of affected files, see KB4012212.