Microsoft provided cumulative Spectre and Meltdown protection with Windows 7 Monthly Rollup KB4088875 and security update KB4088878. However, many users have experienced various issues after installing the respective patches.
As a result, Microsoft rolled out a new update for Windows 7 Service Pack 1 and Windows Server 2008 R2 to fix these problems.
KB4099950 is a maintenance update to fix the problems with the virtual network adapters caused by the security updates of Patch Tuesday in March. The bug was replacing the existing adapter and breaking down network connections as Microsoft said:
A new Ethernet Network Interface Card (NIC) that has default settings may replace the previously existing NIC, causing network issues after you apply this update. Any custom settings on the previous NIC persist in the registry but are unused
Windows 7 KB4099950 fixes NIC settings and IP address issues