CVE-2026-20828
📋 TL;DR
This vulnerability allows an unauthorized attacker with physical access to a Windows system to read memory beyond intended boundaries through Windows Internet Connection Sharing (ICS), potentially disclosing sensitive information. It affects Windows systems with ICS enabled. The risk is limited to attackers with physical access to vulnerable systems.
💻 Affected Systems
- Windows Internet Connection Sharing (ICS)
📦 What is this software?
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 23h2 by Microsoft
Windows 11 24h2 by Microsoft
Windows 11 25h2 by Microsoft
⚠️ Risk & Real-World Impact
Worst Case
An attacker with physical access could read sensitive memory contents, potentially exposing credentials, encryption keys, or other confidential data stored in memory.
Likely Case
Limited information disclosure from adjacent memory locations, possibly revealing non-critical system information or application data.
If Mitigated
No impact if physical access controls prevent unauthorized access to systems or if ICS is disabled.
🎯 Exploit Status
Requires physical access to the system and knowledge of how to trigger the out-of-bounds read condition in ICS.
🛠️ 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-2026-20828
Restart Required: Yes
Instructions:
1. Apply the latest Windows security updates from Microsoft. 2. Restart the system to complete the installation. 3. Verify the update was successfully applied using Windows Update history.
🔧 Temporary Workarounds
Disable Internet Connection Sharing
windowsDisable the ICS feature to eliminate the vulnerability vector
netsh wlan set hostednetwork mode=disallow
Disable ICS through Network Connections properties
🧯 If You Can't Patch
- Disable Internet Connection Sharing feature on all vulnerable systems
- Implement strict physical access controls to prevent unauthorized physical access to systems
🔍 How to Verify
Check if Vulnerable:
Check if ICS is enabled in Network Connections properties or via 'netsh wlan show hostednetwork' commandCheck Version:
systeminfo | findstr /B /C:"OS Name" /C:"OS Version"Verify Fix Applied:
Verify Windows Update history contains the relevant security update KB number📡 Detection & Monitoring
Log Indicators:
- Unexpected ICS service crashes
- Memory access violations in system logs
- Unauthorized physical access events
Network Indicators:
- Unusual ICS configuration changes
- ICS service restart patterns
SIEM Query:
EventID=1000 OR EventID=1001 Source="Application Error" AND Process Name contains "svchost" AND Command Line contains "ics"