This update includes quality improvements. No new operating system features are being introduced and no new security updates are included. Key changes include:
Improved support in Microsoft Cryptographic Application Programming Interface (CryptoAPI) to help identify websites that use Secure Hash Algorithm 1 (SHA-1).
Addressed issue in Microsoft Secure Channel (SChannel) that sometime causes Transport Layer Security (TLS) 1.2 connections to fail depending on whether the root certificate is configured as part of the certificate chain for server authentication.
For more info about how to get this update and a complete list of affect files, see KB3172605.