CVE-2025-47170: Microsoft 365 Apps Use-After-Free Flaw

CVE-2025-47170 Overview

CVE-2025-47170 is a use after free vulnerability in Microsoft Office Word that allows an unauthorized attacker to execute arbitrary code locally. This memory corruption flaw occurs when Word improperly handles memory after it has been freed, creating an opportunity for attackers to hijack program execution flow and run malicious code within the context of the current user.

Critical Impact

Successful exploitation of this use after free vulnerability could allow an attacker to execute arbitrary code with the privileges of the current user, potentially leading to complete system compromise, data exfiltration, or further malware deployment.

Affected Products

• Microsoft 365 Apps for Enterprise
• Microsoft Office Long Term Servicing Channel 2024 (Windows)
• Microsoft Office Long Term Servicing Channel 2024 (macOS)

Discovery Timeline

• 2025-06-10 - CVE-2025-47170 published to NVD
• 2025-07-09 - Last updated in NVD database

Technical Details for CVE-2025-47170

Vulnerability Analysis

This vulnerability is classified as CWE-416 (Use After Free), a type of memory corruption flaw that occurs when a program continues to use a pointer after the memory it references has been freed. In the context of Microsoft Office Word, this condition can be triggered when processing specially crafted document content.

The attack requires local access and user interaction, meaning an attacker must convince a user to open a malicious Word document. Once opened, the document exploits the use after free condition to corrupt memory and redirect execution flow. The impact is significant as successful exploitation grants the attacker the ability to execute arbitrary code with full confidentiality, integrity, and availability impact on the affected system.

Root Cause

The root cause of CVE-2025-47170 lies in improper memory management within Microsoft Office Word. Specifically, the application fails to properly track memory allocation states, allowing a pointer to be dereferenced after the memory region it points to has been deallocated. This creates a dangling pointer condition that attackers can exploit by reallocating the freed memory with attacker-controlled data before the pointer is reused.

Attack Vector

The attack vector for CVE-2025-47170 is local, requiring user interaction to execute. An attacker would typically deliver the exploit through:

1. A malicious Word document (.docx, .doc, or related formats) sent via email
2. A compromised file shared through cloud storage or file sharing services
3. A weaponized document hosted on a malicious website

When the victim opens the malicious document, Word processes the crafted content which triggers the use after free condition. The attacker's payload then executes with the privileges of the user who opened the document. No special privileges are required to exploit this vulnerability, making it accessible to a wide range of threat actors.

The vulnerability mechanism exploits the timing between memory deallocation and subsequent access. When Word processes certain document elements, memory may be freed prematurely while references to that memory persist. Subsequent operations that access this freed memory can be manipulated by an attacker who has reallocated the memory region with malicious content. For technical details, refer to the Microsoft Security Response Center advisory.

Detection Methods for CVE-2025-47170

Indicators of Compromise

• Unusual child processes spawned from WINWORD.EXE or Office-related processes
• Suspicious memory access patterns or crash dumps from Word indicating heap corruption
• Word documents with obfuscated or anomalous embedded content received from unknown sources
• Endpoint detection alerts related to code injection or memory manipulation in Office applications

Detection Strategies

• Deploy endpoint detection and response (EDR) solutions to monitor for anomalous behavior in Microsoft Office processes
• Implement document scanning at email gateways to identify potentially malicious attachments before delivery
• Enable memory protection features such as Data Execution Prevention (DEP) and Address Space Layout Randomization (ASLR)
• Monitor for suspicious process creation events where WINWORD.EXE spawns unexpected child processes

Monitoring Recommendations

• Configure SentinelOne agents to monitor Microsoft Office applications for behavioral anomalies and exploitation attempts
• Enable enhanced logging for Office application events and correlate with security information and event management (SIEM) systems
• Implement file integrity monitoring for Office application binaries and related DLLs
• Review Office application crash reports for signs of exploitation attempts

How to Mitigate CVE-2025-47170

Immediate Actions Required

• Apply the latest security updates from Microsoft for all affected Microsoft 365 and Office LTSC products immediately
• Enable Protected View and Application Guard for Office to isolate potentially malicious documents
• Educate users to avoid opening Word documents from untrusted or unknown sources
• Consider blocking macro-enabled Office documents at the email gateway level until patches are applied

Patch Information

Microsoft has addressed this vulnerability through security updates. Organizations should apply the latest cumulative updates for Microsoft 365 Apps and Office LTSC 2024. Refer to the Microsoft Security Response Center advisory for specific patch versions and download links.

Administrators should prioritize patching based on the high severity rating and ensure all endpoints running affected versions of Microsoft Word receive updates through Windows Update, Microsoft Update, or enterprise deployment tools such as Microsoft Endpoint Configuration Manager.

Workarounds

• Enable Protected View for all documents originating from the internet, email attachments, and potentially unsafe locations
• Configure Microsoft Office Application Guard to open untrusted documents in an isolated container
• Implement restrictive group policies to limit Office macro execution and external content loading
• Use the Office cloud policy service to enforce security baselines across the organization

# PowerShell: Enable Protected View via registry for all Office applications
Set-ItemProperty -Path "HKCU:\Software\Microsoft\Office\16.0\Word\Security\ProtectedView" -Name "DisableInternetFilesInPV" -Value 0 -Type DWord
Set-ItemProperty -Path "HKCU:\Software\Microsoft\Office\16.0\Word\Security\ProtectedView" -Name "DisableAttachementsInPV" -Value 0 -Type DWord
Set-ItemProperty -Path "HKCU:\Software\Microsoft\Office\16.0\Word\Security\ProtectedView" -Name "DisableUnsafeLocationsInPV" -Value 0 -Type DWord