CVE-2025-49661
📋 TL;DR
This vulnerability allows an authorized attacker to exploit an untrusted pointer dereference in the Windows Ancillary Function Driver for WinSock to elevate privileges locally. It affects Windows systems with the vulnerable driver component. Attackers need initial access to the system to exploit this vulnerability.
💻 Affected Systems
- Windows Ancillary Function Driver for WinSock (afd.sys)
📦 What is this software?
Windows 10 1507 by Microsoft
Windows 10 1507 by Microsoft
Windows 10 1607 by Microsoft
Windows 10 1607 by Microsoft
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
Full system compromise with SYSTEM privileges, enabling complete control over the affected Windows system, data theft, and lateral movement.
Likely Case
Privilege escalation from a standard user account to administrator or SYSTEM level, allowing installation of malware, persistence mechanisms, or credential harvesting.
If Mitigated
Limited impact if proper privilege separation exists and users operate with minimal necessary privileges, though local attackers could still gain elevated access.
🎯 Exploit Status
Exploitation requires local access and understanding of Windows kernel driver internals. No public exploit code is known at this time.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Check Microsoft's monthly security updates for the specific KB number
Vendor Advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2025-49661
Restart Required: Yes
Instructions:
1. Open Windows Update settings
2. Check for updates
3. Install all available security updates
4. Restart the system when prompted
🔧 Temporary Workarounds
Restrict user privileges
windowsLimit user accounts to standard privileges to reduce impact of successful exploitation
Enable Windows Defender Exploit Guard
windowsConfigure Exploit Guard to provide additional protection against privilege escalation attempts
🧯 If You Can't Patch
- Implement strict least privilege access controls for all user accounts
- Monitor for suspicious privilege escalation attempts using security tools and audit logs
🔍 How to Verify
Check if Vulnerable:
Check Windows version and installed updates against Microsoft's advisory. Use: wmic qfe list | findstr KB[number]Check Version:
winverVerify Fix Applied:
Verify the specific security update KB number is installed via Windows Update history or wmic command📡 Detection & Monitoring
Log Indicators:
- Unusual privilege escalation events in Windows Security logs (Event ID 4672, 4688)
- Suspicious driver loading or modification events
Network Indicators:
- Not applicable - this is a local privilege escalation vulnerability
SIEM Query:
EventID=4672 OR EventID=4688 | where PrivilegeList contains 'SeDebugPrivilege' OR 'SeTcbPrivilege'