Just days after Microsoft killed security updates for 500 million Windows 10 users, there’s bad news for Windows 11 users as well. A new, mandatory security update is a “total disaster” and an emergency update has suddenly been confirmed.
The warning comes courtesy of Windows Latest. Microsoft admits that Windows 11 KB5066835 breaks localhost connections, “which means locally hosted apps can no longer connect to your network.” But there are also multiple installation failures and bugs blocking peripherals and accessories from working properly.
Users going online to fix update issues are being warned to stop. “Don’t try your luck with internet solutions. They don’t work.” Instead, wait for the update.
“Microsoft says it’s rolling out an emergency patch that should address localhost-related issues in Windows 11 24H2/25H2, but remember, the hotfix could take longer than 48 hours to show on affected PCs.” Meanwhile, Microsoft says “affected users should check for updates and reboot their PC, even if they do not see any newer updates listed.”
Windows Latest has found a “regression in the kernel-mode HTTP server (HTTP.sys). When a browser or app tries to connect to HTTP/2 to services hosted on 127.0.0.1, HTTP.sys mishandles the HTTP/2 handshake/frames and resets the connection.”
The website warns that this is significant “because the Windows update broke IIS, which affects anything behind HTTP.sys. Windows is designed to handle 127.0.0.1 requests by loading TTP/2 session in the kernel, which then sends the request to the IIS worker, ASP.NET Core Module or your app.”
Separately, accessory failures affect “some Logitech peripherals” and “mouse and keyboard not working in WinRE (Windows Recovery Environment).”
As ever, there are a number of green-fingered workarounds for these various issues, but for almost all Windows 11 users, the reality is you’ll await the emergency update if you’re affected. It’s likely that will be here quickly, likely within a day or two.
If you’re still running Windows 10 and reading this with a sense of relief, just make sure you’ve updated your PC with the last ever security fixes you will receive unless and until you enroll in the 12-month ESU program to keep Windows 10 until 2026.
As TechRadar warns, “Windows 10’s final patch fixes a bewildering number of security flaws – and shows why you need extended updates.”
It’s a timely warning, and if you didn’t like the account-driven options to extend security updates for free, you can now buy another year of support in the Microsoft Store.