CVE-2025-49740
📋 TL;DR
This vulnerability allows attackers to bypass Windows SmartScreen security protections over a network, potentially enabling the execution of malicious files without proper warnings. It affects Windows systems with SmartScreen enabled, primarily impacting users who interact with untrusted network content.
💻 Affected Systems
- Windows SmartScreen
📦 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 bypass of SmartScreen protections leading to silent execution of malware, ransomware deployment, or system compromise without user warnings.
Likely Case
Attackers trick users into running malicious files that appear legitimate, leading to malware infections, data theft, or credential harvesting.
If Mitigated
With proper network segmentation and endpoint protection, impact limited to isolated systems with minimal lateral movement.
🎯 Exploit Status
Network-based exploitation suggests relatively straightforward attack vectors once details are known.
🛠️ 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-2025-49740
Restart Required: Yes
Instructions:
1. Apply latest Windows security updates via Windows Update. 2. For enterprise: Deploy through WSUS or Microsoft Endpoint Manager. 3. Verify update installation and restart systems.
🔧 Temporary Workarounds
Disable SmartScreen (not recommended)
windowsTemporarily disable SmartScreen to prevent bypass, but removes protection against other threats
Not recommended for security
Network segmentation
allRestrict network access to vulnerable systems
🧯 If You Can't Patch
- Implement application allowlisting to restrict unauthorized executables
- Deploy enhanced endpoint detection and response (EDR) solutions
🔍 How to Verify
Check if Vulnerable:
Check Windows version and update status in Settings > Windows Update > Update historyCheck Version:
winverVerify Fix Applied:
Verify latest security updates are installed and SmartScreen functions properly with test files📡 Detection & Monitoring
Log Indicators:
- SmartScreen bypass events in Windows Event Logs
- Unexpected file executions without SmartScreen prompts
Network Indicators:
- Unusual network file transfers to Windows systems
- Suspicious SMB or HTTP traffic patterns
SIEM Query:
EventID=4688 AND ProcessName contains suspicious.exe AND ParentProcess contains network-related