CVE-2025-53735
📋 TL;DR
This vulnerability is a use-after-free memory corruption flaw in Microsoft Office Excel that allows an attacker to execute arbitrary code on a victim's system by tricking them into opening a malicious Excel file. It affects users running vulnerable versions of Microsoft Excel on Windows systems.
💻 Affected Systems
- Microsoft Office Excel
📦 What is this software?
365 Apps by Microsoft
365 Apps by Microsoft
Excel by Microsoft
Excel 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 →
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 →
⚠️ 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 persistent backdoor installation.
Likely Case
Local code execution with user-level privileges, enabling data exfiltration, credential harvesting, or lateral movement within the network.
If Mitigated
Limited impact if macros are disabled, file execution is restricted, and proper endpoint protection is in place.
🎯 Exploit Status
Requires social engineering to deliver malicious file; exploitation depends on memory layout and mitigations
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Check Microsoft Security Update Guide for specific version
Vendor Advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2025-53735
Restart Required: Yes
Instructions:
1. Open Excel and go to File > Account
2. Click Update Options > Update Now
3. Alternatively, use Windows Update for Microsoft 365 installations
4. Restart Excel/computer if prompted
🔧 Temporary Workarounds
Disable Excel file opening
windowsTemporarily block Excel files from unknown sources
Enable Protected View
windowsForce all Excel files from internet/email to open in Protected View
File > Options > Trust Center > Trust Center Settings > Protected View > Enable all three options
🧯 If You Can't Patch
- Implement application whitelisting to block unauthorized Excel execution
- Use email filtering to block Excel attachments from untrusted sources
🔍 How to Verify
Check if Vulnerable:
Check Excel version against patched versions in Microsoft advisoryCheck Version:
In Excel: File > Account > About ExcelVerify Fix Applied:
Verify Excel version is updated to patched version and test with known safe files📡 Detection & Monitoring
Log Indicators:
- Excel crash logs with memory access violations
- Unexpected Excel child processes spawning
Network Indicators:
- Unusual outbound connections from Excel process
SIEM Query:
Process creation where parent_process contains 'excel.exe' and command_line contains unusual parameters