CVE-2025-49730
📋 TL;DR
A Time-of-Check Time-of-Use (TOCTOU) race condition vulnerability in Microsoft Windows QoS scheduler allows authenticated attackers to escalate privileges locally. This affects Windows systems where an attacker can execute code with standard user privileges and exploit the race condition to gain SYSTEM-level access. Only Windows systems with the vulnerable QoS scheduler component are affected.
💻 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
Complete system compromise with SYSTEM privileges, allowing installation of persistent malware, credential theft, and lateral movement across the network.
Likely Case
Local privilege escalation from standard user to SYSTEM, enabling attackers to bypass security controls, install backdoors, and access sensitive system resources.
If Mitigated
Limited impact with proper privilege separation, application control policies, and endpoint protection that can detect privilege escalation attempts.
🎯 Exploit Status
TOCTOU race conditions require precise timing and may be challenging to exploit reliably. Requires authenticated access to the system.
🛠️ 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-2025-49730
Restart Required: Yes
Instructions:
1. Apply the latest Windows security updates from Microsoft. 2. Install the specific patch for CVE-2025-49730. 3. Restart the system as required.
🔧 Temporary Workarounds
Disable QoS Scheduler
windowsDisable the Quality of Service scheduler service to mitigate the vulnerability
sc config qwave start= disabled
sc stop qwave
🧯 If You Can't Patch
- Implement strict application control policies to prevent unauthorized code execution
- Use endpoint detection and response (EDR) solutions configured to alert on privilege escalation attempts
🔍 How to Verify
Check if Vulnerable:
Check if QoS scheduler service (qwave) is running and verify Windows version against affected versionsCheck Version:
systeminfo | findstr /B /C:"OS Name" /C:"OS Version"Verify Fix Applied:
Verify that the latest Windows security updates are installed and check that the specific KB patch for CVE-2025-49730 is present📡 Detection & Monitoring
Log Indicators:
- Event ID 4688 with process creation from suspicious locations
- Unexpected privilege escalation events in security logs
- QoS scheduler service manipulation attempts
Network Indicators:
- Unusual outbound connections following local privilege escalation
SIEM Query:
EventID=4688 AND (ProcessName="*qwave*" OR CommandLine="*qwave*") | stats count by host, user