CVE-2025-49695: Microsoft 365 Apps Use After Free Flaw

CVE-2025-49695 Overview

CVE-2025-49695 is a use after free vulnerability in Microsoft Office that allows an unauthorized attacker to execute code locally. This memory corruption flaw (CWE-416) occurs when the application references memory after it has been freed, potentially allowing attackers to manipulate program execution flow and achieve arbitrary code execution on affected systems.

Critical Impact

Successful exploitation of this vulnerability enables local code execution without requiring user privileges, potentially leading to complete system compromise, data theft, or installation of persistent malware on affected Microsoft Office installations.

Affected Products

• Microsoft 365 Apps for Enterprise (x64 and x86)
• Microsoft Office 2016, 2019 (x64 and x86)
• Microsoft Office for Android
• Microsoft Office LTSC 2021 (Windows x64/x86 and macOS)
• Microsoft Office LTSC 2024 (Windows x64/x86 and macOS)

Discovery Timeline

• 2025-07-08 - CVE-2025-49695 published to NVD
• 2025-07-15 - Last updated in NVD database

Technical Details for CVE-2025-49695

Vulnerability Analysis

This use after free vulnerability exists within Microsoft Office's memory management routines. Use after free (UAF) vulnerabilities occur when an application continues to use a pointer after the memory it references has been deallocated. In the context of Microsoft Office, this creates a dangerous condition where freed memory can be reallocated for different purposes, and subsequent access through the dangling pointer can lead to unintended behavior.

The vulnerability allows an unauthorized attacker to execute code locally without requiring any user privileges. The attack complexity is low, meaning exploitation does not require specialized conditions or extensive preparation. All three impact categories—confidentiality, integrity, and availability—can be fully compromised upon successful exploitation.

Root Cause

The root cause of CVE-2025-49695 is improper memory lifecycle management within Microsoft Office components. Specifically, the vulnerability stems from a failure to properly invalidate pointers after their associated memory has been freed. This creates a race condition where the freed memory region can be reallocated and populated with attacker-controlled data before the dangling pointer is dereferenced.

Use after free vulnerabilities in complex applications like Microsoft Office often arise from:

• Asynchronous event handling where object destruction timing is non-deterministic
• Complex object hierarchies with shared ownership semantics
• Callback functions that retain references to objects beyond their intended lifetime

Attack Vector

The attack vector for CVE-2025-49695 is local, requiring the attacker to have some level of access to the target system or to trick a user into opening a malicious document. Exploitation typically involves crafting a specially formatted Office document that triggers the vulnerable code path.

The attack flow generally follows this pattern: An attacker creates a malicious document that triggers memory allocation and deallocation sequences in a specific order. By carefully controlling the timing and content of subsequent allocations, the attacker can place controlled data in the freed memory region. When the application later dereferences the dangling pointer, it operates on attacker-controlled data, potentially allowing arbitrary code execution.

Since no user interaction is required once the document is opened and no special privileges are needed, this vulnerability presents a significant risk to organizations using affected Microsoft Office products.

Detection Methods for CVE-2025-49695

Indicators of Compromise

• Unusual Microsoft Office process behavior including unexpected child process spawning
• Memory access violations or crashes in Office applications that may indicate exploitation attempts
• Suspicious Office document files with unusual embedded objects or malformed structures
• Unexpected network connections initiated by Office processes following document opening

Detection Strategies

• Deploy endpoint detection and response (EDR) solutions capable of monitoring Office application memory operations and detecting exploitation attempts
• Implement application whitelisting to prevent unauthorized code execution from Office processes
• Monitor for Office applications spawning unexpected child processes such as cmd.exe, powershell.exe, or scripting engines
• Utilize behavioral analysis to detect anomalous Office application activity patterns

Monitoring Recommendations

• Enable detailed logging for Microsoft Office applications and forward logs to a centralized SIEM platform
• Configure Windows Defender Attack Surface Reduction (ASR) rules specific to Office applications
• Monitor file system activity for Office applications writing to unusual locations
• Implement network segmentation and monitor for lateral movement attempts originating from compromised workstations

How to Mitigate CVE-2025-49695

Immediate Actions Required

• Apply Microsoft security updates immediately for all affected Office installations across the organization
• Review and update Microsoft Office deployments to ensure all versions are current and patched
• Enable Protected View and Application Guard for Office to provide additional sandboxing protection
• Implement strict email attachment policies to quarantine and scan Office documents before delivery to end users

Patch Information

Microsoft has released security updates to address CVE-2025-49695. Organizations should consult the Microsoft Security Response Center advisory for specific patch information and deployment guidance. Updates are available through standard Microsoft update channels including Windows Update, Microsoft Update Catalog, and enterprise deployment tools such as WSUS and Configuration Manager.

The security updates address the underlying memory management issue by implementing proper pointer invalidation after memory deallocation and adding additional validation checks before memory access operations.

Workarounds

• Enable Protected View for all Office documents from untrusted sources to limit the impact of potential exploitation
• Utilize Microsoft Defender Application Guard for Office to isolate potentially malicious documents in a virtualized container
• Implement strict group policies to disable macros and active content in Office documents from external sources
• Consider using Office Online or web-based alternatives for viewing documents from untrusted sources until patches can be applied

Organizations should consult the official Microsoft advisory for the most current mitigation guidance and patch availability information.