CVE-2026-20867
📋 TL;DR
This CVE describes a race condition vulnerability in Windows Management Services that allows an authenticated attacker to escalate privileges on a local system. Attackers can exploit improper synchronization in shared resource handling to gain higher privileges than intended. This affects Windows systems with the vulnerable Windows Management Services component.
💻 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/administrator privileges, enabling persistence, lateral movement, and data exfiltration.
Likely Case
Local privilege escalation from standard user to administrator/SYSTEM level, allowing installation of malware, disabling security controls, and accessing sensitive data.
If Mitigated
Limited impact with proper privilege separation, application control policies, and monitoring in place.
🎯 Exploit Status
Race condition exploitation requires precise timing and local access. No public exploit code available at this time.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: To be specified in Microsoft Security Update
Vendor Advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-20867
Restart Required: Yes
Instructions:
1. Check Microsoft Security Update Guide for CVE-2026-20867. 2. Apply the relevant Windows security update through Windows Update. 3. Restart the system as required.
🔧 Temporary Workarounds
Disable Windows Management Services
windowsDisable the vulnerable service if not required for operations
sc config WinMgmt start= disabled
sc stop WinMgmt
Implement Least Privilege
allEnsure users operate with minimal necessary privileges
🧯 If You Can't Patch
- Implement strict access controls and monitor for privilege escalation attempts
- Use application control solutions to prevent unauthorized process execution
🔍 How to Verify
Check if Vulnerable:
Check Windows version and installed updates against Microsoft's advisory for CVE-2026-20867Check Version:
systeminfo | findstr /B /C:"OS Name" /C:"OS Version"Verify Fix Applied:
Verify the security update for CVE-2026-20867 is installed via Windows Update history or systeminfo command📡 Detection & Monitoring
Log Indicators:
- Unusual process creation with elevated privileges
- Windows Management Services access patterns
- Security log Event ID 4688 with privilege changes
Network Indicators:
- Local system activity only - no network indicators
SIEM Query:
EventID=4688 AND (NewProcessName contains "powershell" OR NewProcessName contains "cmd") AND SubjectUserName!=SYSTEM AND TokenElevationType="%%1938"