localhost connectivity

Microsoft's latest mandatory security update for Windows 11, KB5066835, has caused significant disruptions, including inoperable localhost connections and multiple installation failures. Users are experiencing issues with locally hosted applications, and the update has also affected certain Logitech peripherals and mouse and keyboard functionality in the Windows Recovery Environment (WinRE). Microsoft has acknowledged these problems and plans to release an emergency fix within 48 hours. A regression in the kernel-mode HTTP server (HTTP.sys) is responsible for the localhost connectivity issues, particularly impacting Internet Information Services (IIS). Users are advised against seeking online troubleshooting solutions, as they have proven ineffective, and some have found risky temporary workarounds.