CVE-2025-21395
📋 TL;DR
This vulnerability allows remote attackers to execute arbitrary code on systems running vulnerable versions of Microsoft Access. Attackers can exploit this by tricking users into opening specially crafted Access files, potentially leading to full system compromise. Organizations using Microsoft Access are affected.
💻 Affected Systems
- Microsoft Access
📦 What is this software?
365 Apps by Microsoft
365 Apps by Microsoft
Access by Microsoft
Office 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 →
⚠️ Risk & Real-World Impact
Worst Case
Complete system takeover with administrative privileges, data theft, ransomware deployment, and lateral movement across the network.
Likely Case
Malware installation, credential harvesting, and data exfiltration from the compromised system.
If Mitigated
Limited impact due to application sandboxing, user privilege restrictions, and network segmentation.
🎯 Exploit Status
Requires social engineering to deliver malicious file. No known active exploitation at time of disclosure.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: To be determined from Microsoft's monthly security updates
Vendor Advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2025-21395
Restart Required: No
Instructions:
1. Apply latest Microsoft security updates via Windows Update. 2. For enterprise deployments, deploy patches through WSUS or Microsoft Endpoint Configuration Manager. 3. Verify patch installation in affected systems.
🔧 Temporary Workarounds
Block Access file execution via Group Policy
WindowsPrevent execution of Access files from untrusted sources
Disable macros and ActiveX controls
allConfigure Access to disable potentially dangerous content
🧯 If You Can't Patch
- Restrict user permissions to prevent administrative access
- Implement application whitelisting to block unauthorized Access file execution
🔍 How to Verify
Check if Vulnerable:
Check Microsoft Access version against patched versions in security bulletinCheck Version:
wmic product where name="Microsoft Access" get versionVerify Fix Applied:
Verify patch is installed via Windows Update history or system registry📡 Detection & Monitoring
Log Indicators:
- Unusual Access process creation, unexpected file access patterns, crash dumps from Access
Network Indicators:
- Outbound connections from Access process to unknown IPs, unusual DNS queries
SIEM Query:
Process Creation where Image contains "MSACCESS.EXE" and CommandLine contains suspicious patterns