CVE-2025-47973
📋 TL;DR
A buffer over-read vulnerability in Virtual Hard Disk (VHDX) handling allows local attackers to read beyond allocated memory boundaries. This can lead to privilege escalation on affected systems. The vulnerability affects systems using VHDX virtual disk files.
💻 Affected Systems
- Microsoft Windows
- Hyper-V
- Azure Stack HCI
📦 What is this software?
Windows 10 1507 by Microsoft
Windows 10 1507 by Microsoft
Windows 10 1607 by Microsoft
Windows 10 1607 by Microsoft
Windows 10 1809 by Microsoft
Windows 10 1809 by Microsoft
Windows 10 21h2 by Microsoft
Windows 10 22h2 by Microsoft
Windows 11 22h2 by Microsoft
Windows 11 23h2 by Microsoft
Windows 11 24h2 by Microsoft
⚠️ Risk & Real-World Impact
Worst Case
Complete system compromise through privilege escalation to SYSTEM/root level, allowing attacker to install malware, steal credentials, or pivot to other systems.
Likely Case
Local privilege escalation allowing attackers to gain administrative privileges on compromised systems.
If Mitigated
Limited impact if proper access controls and monitoring are in place, though privilege escalation risk remains.
🎯 Exploit Status
Requires local access and knowledge of memory layout. No public exploit code available at this time.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: To be determined via Microsoft's monthly security updates
Vendor Advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2025-47973
Restart Required: Yes
Instructions:
1. Check Microsoft's security advisory for patch availability. 2. Apply the latest Windows security updates via Windows Update. 3. Restart the system as required.
🔧 Temporary Workarounds
Restrict VHDX file access
windowsLimit access to VHDX files to trusted users only
icacls *.vhdx /inheritance:r /grant:r "Administrators:(F)" /grant:r "SYSTEM:(F)"
Disable unnecessary VHDX mounting
windowsPrevent automatic mounting of untrusted VHDX files
🧯 If You Can't Patch
- Implement strict access controls on VHDX files and virtual disk operations
- Monitor for suspicious privilege escalation attempts and VHDX file access patterns
🔍 How to Verify
Check if Vulnerable:
Check system version against Microsoft's advisory and verify if VHDX functionality is enabledCheck Version:
wmic os get caption,version,buildnumberVerify Fix Applied:
Verify Windows Update history shows the relevant security patch installed and system version matches patched version📡 Detection & Monitoring
Log Indicators:
- Unusual VHDX file access patterns
- Privilege escalation attempts
- Failed authentication events followed by successful high-privilege operations
Network Indicators:
- Lateral movement following local privilege escalation
SIEM Query:
EventID=4688 AND (ProcessName LIKE '%vhdx%' OR CommandLine LIKE '%vhdx%') AND NewProcessName LIKE '%powershell%' OR '%cmd%'