CVE-2025-54904
📋 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. Successful exploitation requires user interaction to open a specially crafted document.
💻 Affected Systems
- Microsoft 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
Complete system compromise with attacker gaining full control of the victim's computer, enabling data theft, ransomware deployment, or lateral movement within the network.
Likely Case
Local code execution with the privileges of the current user, potentially leading to data exfiltration, credential harvesting, or installation of persistent malware.
If Mitigated
Limited impact if macros are disabled, files are opened in Protected View, or user has limited privileges, though memory corruption could still cause application crashes.
🎯 Exploit Status
Exploitation requires user interaction to open malicious file; use-after-free vulnerabilities often require precise memory manipulation but are frequently weaponized once understood
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Check Microsoft's monthly security updates for specific version numbers
Vendor Advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2025-54904
Restart Required: Yes
Instructions:
1. Open any Office application. 2. Go to File > Account > Update Options > Update Now. 3. Alternatively, use Windows Update for Microsoft 365 apps. 4. For enterprise deployments, deploy through Microsoft Endpoint Configuration Manager or equivalent patch management system.
🔧 Temporary Workarounds
Disable automatic opening of Excel files
windowsConfigure Excel to open files in Protected View by default to prevent automatic code execution
Not applicable - configure through Excel Trust Center settings
Block suspicious file types
allConfigure email gateways and web proxies to block .xls, .xlsx, .xlsm files from untrusted sources
Enterprise-specific configuration commands vary by security product
🧯 If You Can't Patch
- Restrict Excel file execution through application control policies (e.g., Windows Defender Application Control)
- Implement least privilege principles so users don't have administrative rights on their workstations
🔍 How to Verify
Check if Vulnerable:
Check Excel version against patched versions in Microsoft Security Update Guide; vulnerable if running unpatched versionCheck Version:
In Excel: File > Account > About Excel (shows version number)Verify Fix Applied:
Verify Excel version matches or exceeds patched version listed in Microsoft advisory; check Windows Update history for Office security updates📡 Detection & Monitoring
Log Indicators:
- Excel crash logs with memory access violations
- Windows Event Logs showing Excel spawning unexpected child processes
- Antivirus alerts for malicious Office documents
Network Indicators:
- Outbound connections from Excel process to suspicious IPs
- DNS requests for command-and-control domains following Excel file opening
SIEM Query:
Example: (process_name="EXCEL.EXE" AND (event_id=1000 OR event_id=1001)) OR (parent_process="EXCEL.EXE" AND process_creation=true)