CVE-2025-62203
📋 TL;DR
This vulnerability is a use-after-free flaw in Microsoft Office Excel that allows an unauthorized 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. The attacker gains the same privileges as the logged-in user.
💻 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 leading to malware installation, credential theft, or data exfiltration from the compromised system.
If Mitigated
Limited impact if user runs with minimal privileges, macros are disabled, and file execution is restricted, potentially resulting in application crash only.
🎯 Exploit Status
Exploitation requires user interaction (opening a file). No public exploit code is known at this time.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Check Microsoft's Security Update Guide for specific patched versions.
Vendor Advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2025-62203
Restart Required: Yes
Instructions:
1. Open any Office application.
2. Go to File > Account (or Office Account).
3. Under Product Information, select Update Options > Update Now.
4. Restart the system if prompted.
🔧 Temporary Workarounds
Block Excel file execution via Group Policy
windowsPrevent execution of Excel files from untrusted sources using application control policies.
Use Windows Group Policy Editor (gpedit.msc) to configure Software Restriction Policies or AppLocker rules.
Disable macros in Excel
windowsSet Excel to disable all macros without notification to prevent malicious macro execution.
In Excel: File > Options > Trust Center > Trust Center Settings > Macro Settings > 'Disable all macros without notification'
🧯 If You Can't Patch
- Restrict user permissions to limit damage if exploited (e.g., run Excel with standard user rights, not admin).
- Implement email filtering to block suspicious Excel attachments and educate users on phishing risks.
🔍 How to Verify
Check if Vulnerable:
Check Excel version against patched versions listed in Microsoft's advisory. Unpatched versions are vulnerable.Check Version:
In Excel: File > Account > About Excel (version displayed).Verify Fix Applied:
Verify Excel has updated to the patched version and no longer crashes with test files (if available).📡 Detection & Monitoring
Log Indicators:
- Windows Event Logs: Application crashes (Event ID 1000) for EXCEL.EXE, suspicious process creation from Excel.
Network Indicators:
- Unusual outbound connections from Excel process to external IPs, especially post-file-open.
SIEM Query:
EventID=1000 AND SourceName="Application Error" AND ProcessName="EXCEL.EXE" | stats count by _time