CVE-2026-25167
📋 TL;DR
CVE-2026-25167 is a use-after-free vulnerability in Microsoft Brokering File System that allows local attackers to execute arbitrary code with elevated privileges. This affects systems running vulnerable versions of Windows where an attacker has initial access. Successful exploitation could lead to complete system compromise.
💻 Affected Systems
- Microsoft Windows
📦 What is this software?
Windows 11 24h2 by Microsoft
Windows 11 24h2 by Microsoft
Windows 11 25h2 by Microsoft
Windows 11 25h2 by Microsoft
Windows 11 26h1 by Microsoft
Windows 11 26h1 by Microsoft
⚠️ Risk & Real-World Impact
Worst Case
Complete system takeover with SYSTEM/administrator privileges, enabling installation of persistent malware, credential theft, and lateral movement across the network.
Likely Case
Local privilege escalation from a standard user account to SYSTEM/administrator level, allowing attackers to bypass security controls and maintain persistence.
If Mitigated
Limited impact if proper privilege separation, application control policies, and endpoint protection are in place to detect and block exploitation attempts.
🎯 Exploit Status
Requires local access and ability to execute code. Use-after-free vulnerabilities typically require careful memory manipulation but have been successfully weaponized in the past for similar Windows components.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Not yet released
Vendor Advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-25167
Restart Required: Yes
Instructions:
1. Monitor Microsoft Security Response Center for patch release. 2. Apply security update through Windows Update when available. 3. Restart system after patch installation.
🔧 Temporary Workarounds
Restrict local user privileges
windowsLimit standard user accounts to prevent initial access that could be leveraged for privilege escalation
Enable exploit protection
windowsUse Windows Defender Exploit Guard to apply exploit protection mitigations
Set-ProcessMitigation -System -Enable DEP,ASLR,CFG
🧯 If You Can't Patch
- Implement strict application control policies to prevent unauthorized code execution
- Deploy endpoint detection and response (EDR) solutions to detect privilege escalation attempts
🔍 How to Verify
Check if Vulnerable:
Check Windows version and compare against Microsoft's advisory when patch is releasedCheck Version:
wmic os get caption,version,buildnumberVerify Fix Applied:
Verify Windows Update history shows the security patch installed and system version matches patched version📡 Detection & Monitoring
Log Indicators:
- Unusual process creation with elevated privileges
- Access violations in Brokering File System components
- Security log events showing privilege escalation
Network Indicators:
- Lateral movement from previously compromised host
- Unusual authentication patterns from elevated accounts
SIEM Query:
EventID=4688 AND NewProcessName CONTAINS 'cmd.exe' OR 'powershell.exe' AND SubjectUserName!=SubjectDomainName AND TokenElevationType=%%1938