CVE-2025-27747
📋 TL;DR
A use-after-free vulnerability in Microsoft Office Word allows attackers to execute arbitrary code on affected systems by tricking users into opening malicious documents. This affects all users running vulnerable versions of Microsoft Word. Successful exploitation requires user interaction to open a specially crafted document.
💻 Affected Systems
- Microsoft Office Word
- Microsoft 365 Apps
- Microsoft Office LTSC
📦 What is this software?
365 Apps by Microsoft
Office by Microsoft
Office Long Term Servicing Channel by Microsoft
View all CVEs affecting Office Long Term Servicing Channel →
Office Long Term Servicing Channel by Microsoft
View all CVEs affecting Office Long Term Servicing Channel →
Office Long Term Servicing Channel by Microsoft
View all CVEs affecting Office Long Term Servicing Channel →
Office Long Term Servicing Channel by Microsoft
View all CVEs affecting Office Long Term Servicing Channel →
Word by Microsoft
⚠️ Risk & Real-World Impact
Worst Case
Full system compromise with attacker gaining the same privileges as the logged-in user, potentially leading to data theft, ransomware deployment, or lateral movement within the network.
Likely Case
Local code execution with user-level privileges, enabling malware installation, credential harvesting, or persistence mechanisms on the compromised system.
If Mitigated
Limited impact due to application sandboxing, restricted user permissions, or macro security settings preventing document execution.
🎯 Exploit Status
Exploitation requires social engineering to deliver malicious documents; no public exploit code available at this time.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Check Microsoft Security Update Guide for specific version numbers
Vendor Advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2025-27747
Restart Required: Yes
Instructions:
1. Open Microsoft Word. 2. Go to File > Account > Update Options > Update Now. 3. Alternatively, use Windows Update for Microsoft 365 updates. 4. Restart system after installation.
🔧 Temporary Workarounds
Disable Word as email editor
windowsPrevents Word from automatically opening email attachments
Open Outlook > File > Options > Mail > Uncheck 'Use Word as email editor'
Block .doc/.docx from untrusted sources
allConfigure email/web filters to block Word documents from unknown senders
🧯 If You Can't Patch
- Implement application whitelisting to restrict Word execution to trusted locations
- Enable macro security settings to block macros from untrusted sources
🔍 How to Verify
Check if Vulnerable:
Check Word version via File > Account > About Word and compare with patched versions in Microsoft advisoryCheck Version:
winword.exe /?Verify Fix Applied:
Verify Word version matches patched version from Microsoft Security Update Guide📡 Detection & Monitoring
Log Indicators:
- Word crash logs with memory access violations
- Windows Event Logs showing Word process spawning unexpected child processes
Network Indicators:
- Outbound connections from Word process to suspicious IPs
- DNS requests for known malicious domains from Office processes
SIEM Query:
Process Creation where (Image contains 'winword.exe' AND CommandLine contains suspicious patterns) OR (ParentImage contains 'winword.exe' AND Image not in approved list)