CVE-2025-27739
📋 TL;DR
This Windows kernel vulnerability allows an authenticated attacker to exploit untrusted pointer dereference to gain elevated local privileges. It affects Windows systems where an attacker already has some level of access and can execute code locally. The vulnerability enables privilege escalation from a lower-privileged account to SYSTEM or administrator level.
💻 Affected Systems
- Microsoft Windows
📦 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 22h2 by Microsoft
Windows 11 23h2 by Microsoft
Windows 11 24h2 by Microsoft
⚠️ Risk & Real-World Impact
Worst Case
Complete system compromise with SYSTEM-level privileges, allowing installation of persistent malware, credential theft, lateral movement, and disabling of security controls.
Likely Case
Local privilege escalation from a standard user account to administrator/SYSTEM privileges, enabling installation of additional malware, persistence mechanisms, and access to sensitive data.
If Mitigated
Limited impact if proper endpoint protection, application control, and least privilege principles are enforced, though successful exploitation would still grant elevated privileges.
🎯 Exploit Status
Exploitation requires local code execution and understanding of Windows kernel internals. CWE-822 (Untrusted Pointer Dereference) typically involves manipulating kernel memory structures.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Check Microsoft's monthly security updates for specific KB numbers
Vendor Advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2025-27739
Restart Required: Yes
Instructions:
1. Apply the latest Windows security updates from Microsoft. 2. For enterprise environments, deploy updates through WSUS, SCCM, or Intune. 3. Restart systems to complete the installation. 4. Verify the update was successfully applied.
🔧 Temporary Workarounds
No known effective workarounds
windowsThis is a kernel-level vulnerability that requires patching. Microsoft typically does not provide workarounds for kernel vulnerabilities.
🧯 If You Can't Patch
- Implement strict application control/whitelisting to prevent unauthorized code execution
- Enforce least privilege principles and use standard user accounts for daily operations
🔍 How to Verify
Check if Vulnerable:
Check Windows Update history for the specific KB patch mentioned in Microsoft's advisory, or use: wmic qfe list | findstr KB[number]Check Version:
winver or systeminfo | findstr /B /C:"OS Name" /C:"OS Version"Verify Fix Applied:
Verify the specific KB patch is installed in Windows Update history and that system is running a patched Windows build version📡 Detection & Monitoring
Log Indicators:
- Windows Security Event ID 4688 (process creation) showing suspicious privilege escalation attempts
- Sysmon Event ID 10 (ProcessAccess) with suspicious access patterns to high-privilege processes
Network Indicators:
- No direct network indicators as this is a local exploit
SIEM Query:
EventID=4688 AND (NewProcessName contains "cmd.exe" OR NewProcessName contains "powershell.exe") AND SubjectUserName!=SYSTEM AND TokenElevationType="%%1938"