CVE-2025-55696
📋 TL;DR
This CVE describes a Time-of-Check Time-of-Use (TOCTOU) race condition vulnerability in the NtQueryInformationToken function in Windows. It allows authenticated attackers to exploit timing inconsistencies to elevate privileges locally on affected systems. This affects Windows systems where users have local access.
💻 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
Windows 11 25h2 by Microsoft
⚠️ Risk & Real-World Impact
Worst Case
An attacker gains SYSTEM-level privileges, enabling complete system compromise, data theft, persistence mechanisms, and lateral movement across the network.
Likely Case
Local privilege escalation from standard user to administrator or SYSTEM privileges, allowing installation of malware, bypassing security controls, and accessing sensitive data.
If Mitigated
Limited impact with proper privilege separation, minimal user rights, and endpoint protection that detects privilege escalation attempts.
🎯 Exploit Status
TOCTOU race conditions require precise timing and may be challenging to exploit reliably; requires local authenticated access.
🛠️ 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-2025-55696
Restart Required: Yes
Instructions:
1. Visit Microsoft Security Update Guide. 2. Search for CVE-2025-55696. 3. Download and install the appropriate security update for your Windows version. 4. Restart the system as required.
🔧 Temporary Workarounds
Restrict Local User Privileges
windowsLimit standard user accounts to minimal necessary privileges to reduce attack surface.
Enable Exploit Protection
windowsUse Windows Defender Exploit Guard or similar tools to add mitigations against privilege escalation.
🧯 If You Can't Patch
- Implement strict access controls and principle of least privilege for all user accounts.
- Deploy endpoint detection and response (EDR) solutions to monitor for privilege escalation attempts.
🔍 How to Verify
Check if Vulnerable:
Check Windows Update history for the specific KB patch related to CVE-2025-55696 or use systeminfo command to verify OS build number against patched versions.Check Version:
systeminfo | findstr /B /C:"OS Name" /C:"OS Version"Verify Fix Applied:
Verify the security update is installed via Windows Update history or by checking the OS build number matches the patched version from Microsoft's advisory.📡 Detection & Monitoring
Log Indicators:
- Windows Security Event Logs showing unexpected privilege escalation (Event ID 4672, 4688)
- Process creation events with elevated privileges from non-admin users
Network Indicators:
- Not applicable as this is a local exploit
SIEM Query:
EventID=4672 OR EventID=4688 | where SubjectUserName != "SYSTEM" AND PrivilegeList contains "SeDebugPrivilege" OR "SeTcbPrivilege"