.NET Framework 4.8 is available on Windows Update, WSUS and MU Catalog 

Updates to .NET Framework 4.8 on Windows 8.1, Server 2012 R2, Server 2012, Windows 7 SP1, and Server 2008 R2 SP1 will continue to be delivered outside of the Windows cumulative update through the existing .NET Framework updates. 

The .NET Framework 4.8 includes an updated toolset as well as improvements in several areas:

• [Runtime] JIT and NGEN Improvements
• [BCL] Updated ZLib
• [BCL] Reducing FIPS Impact on Cryptography
• [WinForms] Accessibility Enhancements
• [WCF] Service Behavior Enhancements
• [WPF] High DPI Enhancements, UIAutomation Improvements 

Announcing .NET Framework 4.8 Early Access build 3673