Microsoft has taken swift action to mitigate a significant issue affecting Hyper-V virtual machines running on Windows Server 2022. The company has rolled out an emergency update, designated as KB5061906, aimed specifically at addressing unexpected freezes and restarts that have been reported, particularly among Azure confidential VMs.
Details of the Update
This cumulative out-of-band (OOB) update supersedes all prior updates and is crucial for maintaining the integrity of services reliant on Azure’s confidential VMs. These virtual machines are specially designed to safeguard data during processing, ensuring that sensitive information remains protected at all times.
According to Microsoft, the update resolves a critical issue within the direct send path for guest physical addresses (GPA). This flaw could cause confidential VMs operating on Hyper-V with Windows Server 2022 to intermittently stop responding or restart, which in turn affects service availability and necessitates manual intervention.
Importantly, Microsoft clarified that while this issue predominantly impacts Azure confidential VMs, standard Hyper-V deployments are largely unaffected, with exceptions being rare cases involving preview or pre-production configurations.
Installation Instructions
Organizations should note that KB5061906 will not be installed automatically on affected servers and will not be delivered via Windows Update. Instead, it can be manually installed using the standalone MSU package available from the Microsoft Update Catalog.
- If your organization has not yet deployed the May 2025 Windows security update (KB5058385) and operates Windows Server 2022 devices with Hyper-V, it is advisable to apply this OOB update.
- Conversely, if your systems are not impacted by the aforementioned issue, there is no necessity to install this update.
This latest update follows a series of emergency patches released in the previous month, which addressed a separate issue that hindered the launching of Windows containers across various Windows Server versions. Furthermore, in October 2023, Microsoft acknowledged that security updates for Windows Server 2019 and 2022 had inadvertently caused boot issues for VMs on Hyper-V hosts, leading to “failed to start” errors.
Reflecting on the past year, Microsoft has consistently responded to similar challenges, including emergency updates released in January and December 2022, which aimed to rectify problems related to the creation and booting of new Hyper-V VMs.
