CVE-2025-49659
📋 TL;DR
CVE-2025-49659 is a buffer over-read vulnerability in Windows TDX.sys that allows an authenticated attacker to read beyond allocated memory boundaries. This can lead to local privilege escalation on affected Windows systems. Only users with valid local credentials can exploit this vulnerability.
💻 Affected Systems
- Microsoft Windows
📦 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
An attacker with valid local credentials could exploit this to gain SYSTEM-level privileges, potentially taking full control of the system, accessing sensitive data, and installing persistent malware.
Likely Case
An authenticated attacker elevates from standard user to administrator privileges, enabling them to bypass security controls, install unauthorized software, or access restricted resources.
If Mitigated
With proper access controls and least privilege principles, the impact is limited as attackers would need valid credentials and the ability to execute code on the target system.
🎯 Exploit Status
Requires authenticated access and ability to execute code. Buffer over-read vulnerabilities typically require specific conditions to achieve reliable exploitation.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Will be specified in Microsoft's monthly security update (Patch Tuesday)
Vendor Advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2025-49659
Restart Required: Yes
Instructions:
1. Open Windows Update Settings
2. Click 'Check for updates'
3. Install all available security updates
4. Restart the system when prompted
🔧 Temporary Workarounds
Restrict Local Access
windowsLimit who has local login access to vulnerable systems
Implement Least Privilege
windowsEnsure users operate with minimal necessary privileges
🧯 If You Can't Patch
- Implement strict access controls and monitor for suspicious privilege escalation attempts
- Segment vulnerable systems from critical assets and implement application allowlisting
🔍 How to Verify
Check if Vulnerable:
Check if the system has received the Microsoft security update for CVE-2025-49659 via Windows Update historyCheck Version:
wmic os get caption,version,buildnumberVerify Fix Applied:
Verify the security update KB number for CVE-2025-49659 is installed in Windows Update history📡 Detection & Monitoring
Log Indicators:
- Unexpected privilege escalation events in Windows Security logs (Event ID 4672, 4688)
- Suspicious process creation with elevated privileges
Network Indicators:
- Not applicable - local vulnerability
SIEM Query:
EventID=4672 OR EventID=4688 | where PrivilegeList contains "SeDebugPrivilege" OR "SeTcbPrivilege"