CVE-2025-47164: Microsoft 365 Apps Use After Free Flaw

CVE-2025-47164 Overview

CVE-2025-47164 is a use-after-free vulnerability in Microsoft Office that allows an unauthorized attacker to execute arbitrary code locally. This memory corruption flaw occurs when Office applications improperly handle memory operations, enabling attackers to leverage dangling pointers to execute malicious code in the context of the current user.

Critical Impact

Successful exploitation allows attackers to execute arbitrary code with the privileges of the current user, potentially leading to complete system compromise, data theft, or lateral movement within an organization.

Affected Products

• Microsoft 365 Apps for Enterprise
• Microsoft Office 2016, 2019, and Android versions
• Microsoft Office Long Term Servicing Channel (LTSC) 2021 and 2024 for Windows and macOS

Discovery Timeline

• June 10, 2025 - CVE-2025-47164 published to NVD
• July 9, 2025 - Last updated in NVD database

Technical Details for CVE-2025-47164

Vulnerability Analysis

This use-after-free vulnerability (CWE-416) occurs when Microsoft Office applications reference memory that has already been deallocated. When an attacker crafts a malicious document that triggers specific memory operations, the application may continue to use a pointer to freed memory. This dangling pointer can be manipulated to redirect program execution to attacker-controlled code.

The vulnerability requires local access to exploit, meaning an attacker would need to convince a user to open a specially crafted Office document or gain local access to the target system. Once exploited, the attacker gains code execution with the same privilege level as the current user, potentially allowing access to sensitive documents, credential theft, or persistence mechanisms.

Root Cause

The root cause is improper memory management in Microsoft Office's document processing components. When certain objects are freed during document parsing or rendering operations, the application fails to properly nullify associated pointers. Subsequent operations that reference these invalid pointers lead to a use-after-free condition, creating an exploitable memory corruption scenario.

Attack Vector

The attack requires local access, meaning exploitation typically involves:

1. Crafting a malicious Office document (Word, Excel, PowerPoint, etc.) designed to trigger the memory corruption
2. Delivering the document to a target user through email, file sharing, or removable media
3. Convincing the victim to open the document in a vulnerable Office application
4. The malicious document triggers the use-after-free condition during parsing
5. Attacker-controlled data overwrites the freed memory region
6. Program execution is redirected to execute arbitrary code

The vulnerability does not require user interaction beyond opening the malicious document, and no special privileges are needed for initial exploitation.

Detection Methods for CVE-2025-47164

Indicators of Compromise

• Unexpected crashes or error messages in Microsoft Office applications when opening documents
• Office processes spawning unexpected child processes (cmd.exe, powershell.exe, etc.)
• Unusual memory access patterns or exception handling in Office application logs
• Suspicious Office documents with abnormal embedded objects or malformed structures

Detection Strategies

• Deploy endpoint detection solutions capable of monitoring Office application behavior for heap corruption and code injection attempts
• Implement application whitelisting to prevent unauthorized processes from being spawned by Office applications
• Enable Windows Defender Exploit Guard with Attack Surface Reduction (ASR) rules targeting Office applications
• Monitor for abnormal Office process activity including suspicious child process creation

Monitoring Recommendations

• Enable detailed logging for Microsoft Office applications and Windows Event Logs
• Configure SIEM rules to alert on Office applications executing shell commands or PowerShell
• Monitor file system activity for Office applications writing to suspicious locations
• Implement network monitoring for potential data exfiltration following document opening

How to Mitigate CVE-2025-47164

Immediate Actions Required

• Apply the latest Microsoft security updates for all affected Office products immediately
• Enable Protected View in Microsoft Office to restrict execution of potentially malicious content
• Configure Office applications to open documents from untrusted sources in Protected View
• Educate users about the risks of opening documents from unknown or untrusted sources

Patch Information

Microsoft has released security updates to address this vulnerability. Organizations should consult the Microsoft Security Response Center advisory for detailed patching guidance and specific update packages for each affected product version. Patches are available for Microsoft 365 Apps, Office 2016, Office 2019, and Office LTSC 2021/2024 editions.

Workarounds

• Enable Protected View for files originating from the Internet, email attachments, and potentially unsafe locations
• Implement Microsoft Office Application Guard where available to isolate document processing
• Restrict macro execution and active content in Office documents using Group Policy
• Consider deploying Office documents through a document sanitization gateway that strips potentially malicious content

# Enable Protected View via registry for Office documents from the Internet
reg add "HKCU\Software\Microsoft\Office\16.0\Word\Security\ProtectedView" /v DisableInternetFilesInPV /t REG_DWORD /d 0 /f
reg add "HKCU\Software\Microsoft\Office\16.0\Excel\Security\ProtectedView" /v DisableInternetFilesInPV /t REG_DWORD /d 0 /f
reg add "HKCU\Software\Microsoft\Office\16.0\PowerPoint\Security\ProtectedView" /v DisableInternetFilesInPV /t REG_DWORD /d 0 /f