CVE-2025-29955
📋 TL;DR
An improper input validation vulnerability in Windows Hyper-V allows local attackers to cause denial of service conditions. This affects systems running Hyper-V virtualization components. Attackers must have local access to exploit this vulnerability.
💻 Affected Systems
- Windows Hyper-V
📦 What is this software?
Windows 11 24h2 by Microsoft
⚠️ Risk & Real-World Impact
Worst Case
Complete system crash or hypervisor failure affecting all virtual machines running on the host
Likely Case
Temporary service disruption affecting specific virtual machines or Hyper-V components
If Mitigated
Limited impact with proper access controls and monitoring in place
🎯 Exploit Status
Requires local access and specific conditions to trigger the input validation flaw
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Check Microsoft Security Update Guide for specific KB numbers
Vendor Advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2025-29955
Restart Required: Yes
Instructions:
1. Apply latest Windows security updates from Microsoft
2. For Hyper-V hosts, apply updates through Windows Update or WSUS
3. Restart affected systems after patch installation
🔧 Temporary Workarounds
Disable Hyper-V if not required
windowsRemove Hyper-V role/feature from systems where virtualization is not needed
Disable-WindowsOptionalFeature -Online -FeatureName Microsoft-Hyper-V-All
Restrict local access
windowsImplement strict access controls to limit who can interact with Hyper-V components
🧯 If You Can't Patch
- Implement strict access controls to limit local user privileges
- Monitor Hyper-V logs for unusual activity or service disruptions
🔍 How to Verify
Check if Vulnerable:
Check if Hyper-V is enabled and system is unpatched: Get-WindowsOptionalFeature -Online -FeatureName Microsoft-Hyper-V-AllCheck Version:
systeminfo | findstr /B /C:"OS Name" /C:"OS Version"Verify Fix Applied:
Verify Windows Update history for Hyper-V related patches and check system is fully updated📡 Detection & Monitoring
Log Indicators:
- Hyper-V service crashes in Event Viewer
- Unexpected Hyper-V component failures
- System event logs showing service disruptions
Network Indicators:
- Sudden loss of connectivity to virtual machines
- Virtual machine migration failures
SIEM Query:
EventID=1000 OR EventID=1001 OR EventID=41 AND Source="Hyper-V" OR ProcessName="vmms.exe"