CVE-2022-26916
📋 TL;DR
CVE-2022-26916 is a remote code execution vulnerability in Windows Fax Compose Form that allows attackers to execute arbitrary code on affected systems. This affects Windows systems with the fax service enabled. Attackers could exploit this by tricking users into opening specially crafted documents.
💻 Affected Systems
- Microsoft Windows
📦 What is this software?
Windows 10 by Microsoft
Windows 10 by Microsoft
Windows 10 by Microsoft
Windows 10 by Microsoft
Windows 10 by Microsoft
Windows 10 by Microsoft
Windows 10 by Microsoft
Windows 11 by Microsoft
Windows 11 by Microsoft
Windows 7 by Microsoft
Windows 8.1 by Microsoft
Windows Rt 8.1 by Microsoft
⚠️ Risk & Real-World Impact
Worst Case
Full system compromise with administrative privileges, allowing data theft, ransomware deployment, or persistent backdoor installation.
Likely Case
Limited user-level code execution leading to credential theft, lateral movement, or malware installation on individual workstations.
If Mitigated
No impact if systems are patched or fax service is disabled; limited to user context if proper application control is in place.
🎯 Exploit Status
Requires user interaction (opening malicious document). No public exploit code available as of last update.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: May 2022 security updates (KB5013942 for Windows 10, KB5013943 for Windows 11, etc.)
Vendor Advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2022-26916
Restart Required: Yes
Instructions:
1. Install May 2022 Windows security updates via Windows Update. 2. For enterprise: Deploy through WSUS or Microsoft Endpoint Configuration Manager. 3. Verify installation in Windows Update history.
🔧 Temporary Workarounds
Disable Fax Service
windowsRemove or disable Windows Fax and Scan service to eliminate attack surface
sc stop Fax
sc config Fax start= disabled
Remove Fax Feature
windowsUninstall fax components from Windows
Dism /online /Disable-Feature /FeatureName:FaxServicesClientPackage
🧯 If You Can't Patch
- Disable fax service on all affected systems
- Implement application control to block execution of fax-related binaries
- Educate users about not opening untrusted documents
🔍 How to Verify
Check if Vulnerable:
Check if fax service is installed and enabled: Get-WindowsOptionalFeature -Online -FeatureName FaxServicesClientPackageCheck Version:
systeminfo | findstr /B /C:"OS Name" /C:"OS Version"Verify Fix Applied:
Verify May 2022 security updates are installed: Get-HotFix -Id KB5013942, KB5013943, or relevant KB for your OS version📡 Detection & Monitoring
Log Indicators:
- Unexpected fax service process execution
- Crash of faxcompose.exe
- Security event 4688 for fax-related processes
Network Indicators:
- None - local exploitation only
SIEM Query:
EventID=4688 AND (NewProcessName:*fax* OR CommandLine:*fax*)