The September 2026 Windows Security Update Breaks RDS
Hey all, Andy here with a quick update on something that’s affecting a lot of RDS deployments right now. Microsoft released (KB5124012 / KB5124008 / KB5122871 / KB5122882 / KB5122876 / KB5123099 / KB5123066 / KB5123065) on September 8th, aka the September Security Update, and it’s screwing up a lot of RDS deployments.
We first learned about it late last week when a customer of ours was experiencing issues with both connection failures and our software’s ability to even display RDS sessions for management.
The primary symptoms that admins encounter are RDP connections that fail to complete or hang when users try to sign on. Microsoft’s only guidance right now is to contact Microsoft Support for Business. And as we know, Microsoft support, if you can even call it that, is pretty much a black hole these days.
How to Remediate The Problem Using KIRs for Group Policy
Fortunately, Bleeping Computer has a great write up on this buggy update and has now published the direct links to download a Known Issue Rollback (KIR) that you can attach to a Group Policy object that rolls back the buggy code in this update that affects RDS. I’ve included a link to their article above so you can find and download the KIR for your particular server OS level of RDS. Also, this article covers how to deploy KIRs into a GPO (e.g. the one tied to your RDS hosts for instance) if you haven’t done this yet to date.
Anyway, I don’t know if this bug in the security update was due to more shoddy QA on Microsoft’s part or a different reason, but Microsoft, maybe stop laying off so many team members and realize that all QA and development can’t be done by AI alone. Fix your crap, please! Admins are already overworked enough as it is.
On a final note, yes, I know I’ve not posted any new updates on my RDPHard YouTube channel in a while. Mostly that was due to our big Remote Desktop Commander Suite v8 release a few months ago that now offers client endpoint and DEX performance monitoring and troubleshooting in RDS and AVD environments. And we have a new version of our Remote Desktop Canary synthetic monitoring tool due for release soon. However, I promise you I’ll have some new full length videos soon covering the newer features in RDS 2025, as well as my thoughts on Azure Virtual Desktop Hybrid. Till then, happy remoting.
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