Microsoft has released an out-of-band (OOB) emergency update to address a critical issue causing some Hyper-V virtual machines (VMs) running on Windows Server 2022 to freeze or restart unexpectedly. The problem primarily affects Azure Confidential VMs, a specialized class of virtual machines designed to secure data during processing, transmission, and storage.

The issue stems from a flaw in the direct send path for guest physical addresses (GPAs), which could lead to intermittent system hangs or reboots, severely impacting service availability. Microsoft has resolved the problem with the release of cumulative update KB5061906, which supersedes all previous updates for Windows Server 2022.

“This issue primarily affects Azure Confidential VMs and is not expected to impact standard in-market Hyper-V deployments, except in rare cases involving preview or pre-production configurations,” the company stated in a support document.

Importantly, KB5061906 will not install automatically and will not be distributed via Windows Update. Affected users must manually download and install the standalone MSU package from the Microsoft Update Catalog.

Microsoft advises organizations with Hyper-V environments on Windows Server 2022 that have not yet deployed the May 2025 Patch Tuesday security update (KB5058385) to prioritize the installation of KB5061906. However, those unaffected by the issue are not required to install the OOB update.

Ongoing Hyper-V Challenges

This marks yet another in a series of emergency patches Microsoft has issued to address Hyper-V-related issues. Just last month, in April, the company rolled out urgent fixes for a known problem that prevented Windows containers from launching on Windows Server 2019, 2022, and 2025 systems.

In October 2023, Microsoft acknowledged that security updates for Windows Server 2019 and 2022 caused virtual machines to fail on Hyper-V hosts, triggering boot failures and “failed to start” errors.

Similar disruptions were seen earlier in 2022, when Microsoft released emergency updates in both January and December to resolve issues that blocked the creation of new Hyper-V VMs or prevented them from booting up.

As Microsoft continues to expand its cloud and virtualization offerings, the company is under pressure to maintain stability in critical enterprise infrastructure — especially for customers relying on secure, confidential computing in the cloud.

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