CVE-2025-26639
📋 TL;DR
An integer overflow vulnerability in the Windows USB Print Driver allows authenticated attackers to execute arbitrary code with elevated privileges. This affects Windows systems with USB printing capabilities where an attacker has local access. The vulnerability enables privilege escalation from a standard user account to SYSTEM-level access.
💻 Affected Systems
- Windows USB Print Driver
📦 What is this software?
Windows 10 21h2 by Microsoft
Windows 10 22h2 by Microsoft
Windows 11 22h2 by Microsoft
Windows 11 22h2 by Microsoft
Windows 11 23h2 by Microsoft
Windows 11 23h2 by Microsoft
Windows 11 24h2 by Microsoft
Windows 11 24h2 by Microsoft
⚠️ Risk & Real-World Impact
Worst Case
Complete system compromise with SYSTEM privileges, enabling installation of persistent malware, credential theft, and lateral movement across the network.
Likely Case
Local privilege escalation allowing attackers to bypass security controls, install additional malware, and access sensitive system resources.
If Mitigated
Limited impact with proper endpoint protection, least privilege enforcement, and network segmentation preventing lateral movement.
🎯 Exploit Status
Requires local authenticated access and knowledge of driver interaction. No public exploit code available at this time.
🛠️ 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-2025-26639
Restart Required: Yes
Instructions:
1. Apply the latest Windows security updates from Microsoft. 2. Restart affected systems. 3. Verify the update was successfully installed via Windows Update history.
🔧 Temporary Workarounds
Disable USB Printing
windowsTemporarily disable USB printing functionality to prevent exploitation
Disable via Device Manager or Group Policy: Computer Configuration > Administrative Templates > Printers > Disable USB printing
Restrict USB Device Installation
windowsUse Group Policy to restrict installation of USB printing devices
gpedit.msc > Computer Configuration > Administrative Templates > System > Device Installation > Device Installation Restrictions
🧯 If You Can't Patch
- Implement strict least privilege principles - ensure users don't have administrative rights
- Deploy endpoint detection and response (EDR) solutions to monitor for privilege escalation attempts
🔍 How to Verify
Check if Vulnerable:
Check Windows Update history for missing security patches related to USB Print DriverCheck Version:
wmic os get caption, version, buildnumber, csdversionVerify Fix Applied:
Verify the security update is installed via Windows Update or by checking system version against patched versions📡 Detection & Monitoring
Log Indicators:
- Event ID 4697: Service installation attempts
- Printer service crashes or unexpected restarts
- Unusual process creation from print spooler
Network Indicators:
- Unusual outbound connections from print servers
- SMB or RPC traffic from non-standard accounts
SIEM Query:
source="windows" AND (event_id=4697 OR process_name="spoolsv.exe") AND (command_line CONTAINS "usb" OR command_line CONTAINS "print")