CVE-2026-20918
📋 TL;DR
A race condition vulnerability in Windows Management Services allows authenticated attackers to escalate privileges on local systems. This affects Windows systems with the vulnerable service enabled, potentially allowing attackers to gain higher privileges than intended.
💻 Affected Systems
- Windows Management Services
📦 What is this software?
Windows 10 1809 by Microsoft
Windows 10 1809 by Microsoft
Windows 10 21h2 by Microsoft
Windows 10 22h2 by Microsoft
Windows 11 23h2 by Microsoft
Windows 11 24h2 by Microsoft
Windows 11 25h2 by Microsoft
⚠️ Risk & Real-World Impact
Worst Case
Complete system compromise with SYSTEM-level privileges, enabling installation of persistent malware, credential theft, and lateral movement across the network.
Likely Case
Local privilege escalation from standard user to administrator or SYSTEM privileges, allowing attackers to bypass security controls and execute arbitrary code.
If Mitigated
Limited impact with proper access controls and monitoring, potentially detected before full exploitation occurs.
🎯 Exploit Status
Requires authenticated access and precise timing to trigger the race condition; exploitation may be challenging but feasible for skilled attackers.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Check Microsoft Security Update for specific KB number
Vendor Advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-20918
Restart Required: Yes
Instructions:
1. Open Windows Update Settings
2. Check for updates
3. Install all security updates
4. Restart system when prompted
🔧 Temporary Workarounds
Disable Windows Management Services
windowsTemporarily disable the vulnerable service to prevent exploitation
sc config Winmgmt start= disabled
sc stop Winmgmt
Restrict Service Permissions
windowsLimit who can start/stop the service to reduce attack surface
sc sdset Winmgmt D:(A;;CCLCSWRPWPDTLOCRRC;;;SY)(A;;CCDCLCSWRPWPDTLOCRSDRCWDWO;;;BA)(A;;CCLCSWLOCRRC;;;IU)(A;;CCLCSWLOCRRC;;;SU)
🧯 If You Can't Patch
- Implement strict access controls to limit who can log into affected systems
- Deploy endpoint detection and response (EDR) solutions to monitor for privilege escalation attempts
🔍 How to Verify
Check if Vulnerable:
Check Windows version and installed updates against Microsoft advisory; verify if Windows Management Service is runningCheck Version:
systeminfo | findstr /B /C:"OS Name" /C:"OS Version"Verify Fix Applied:
Verify the security update KB number is installed via 'wmic qfe list' or PowerShell 'Get-HotFix'📡 Detection & Monitoring
Log Indicators:
- Unexpected service starts/stops of Winmgmt
- Process creation with unexpected parent-child relationships
- Security log events showing privilege escalation
Network Indicators:
- Unusual WMI (Windows Management Instrumentation) traffic patterns
- Lateral movement attempts following local privilege escalation
SIEM Query:
EventID=4688 AND (NewProcessName LIKE '%powershell%' OR NewProcessName LIKE '%cmd%') AND ParentProcessName LIKE '%services.exe%'