Full Report
Microsoft has released an emergency update to address a known issue causing some Hyper-V virtual machines with Windows Server 2022 to freeze or restart unexpectedly. [...]
Analysis Summary
# Vulnerability: Windows Server Emergency Update for Hyper-V Freeze/Restart Issues
## CVE Details
- CVE ID: Not explicitly mentioned in the provided text. This appears to be a security/stability advisory addressed via an Out-of-Band (OOB) update rather than a specifically tracked CVE.
- CVSS Score: N/A (Not specified)
- CWE: N/A (Not specified)
## Affected Systems
- Products: Windows Server running Hyper-V roles.
- Versions: Windows Server 2022 (implied, as the fix recommendation references the May 2025 update KB5058385).
- Configurations: Primarily affects Azure confidential VMs. Standard in-market Hyper-V deployments are generally unaffected except in rare preview/pre-production scenarios.
## Vulnerability Description
The issue causes Hyper-V Virtual Machines (VMs) to freeze or encounter restart issues without adequate warning or predictability, requiring manual intervention to resolve.
## Exploitation
- Status: Not mentioned if this is a vulnerability being actively exploited; the text focuses on a functional/stability issue requiring an emergency update.
- Complexity: N/A
- Attack Vector: N/A
## Impact
- Confidentiality: Unknown/Not specified.
- Integrity: Potential loss of data integrity due to unexpected VM shutdowns/freezing.
- Availability: Direct impact on VM availability leading to service disruption requiring manual recovery.
## Remediation
### Patches
- **KB5061906**: This is the Out-of-Band (OOB) update providing the fix.
- **Installation Note**: KB5061906 will *not* install automatically via Windows Update. It must be installed manually using the standalone MSU package from the Microsoft Update Catalog.
- **Alternative Recommendation**: If an organization has *not* deployed the May 2025 Windows security update (KB5058385), applying KB5061906 instead is recommended for affected environments.
### Workarounds
- If the organization is **not** affected by this specific issue, no action (installation of the OOB update) is required.
## Detection
- **Indicators of Compromise (IoC)**: VMs freezing or unexpectedly restarting on Hyper-V hosts, particularly those utilizing Azure confidential VM features.
- **Detection Methods and Tools**: Monitoring system and event logs for related Hyper-V errors or service failures.
## References
- Vendor Advisories: Microsoft Windows Message Center (learn dot microsoft dot com/en-us/windows/release-health/windows-message-center#3561)
- Relevant Links:
- Information about KB5061906 installation: Microsoft Update Catalog (catalog dot update dot microsoft dot com/Search dot aspx?q=KB5061906)
- Mention of previous related updates (e.g., fixing container launch issues, October 2023 Hyper-V breaks, January/December 2022 VM creation issues).