CVE-2025-47165: Microsoft 365 Apps Use-After-Free Flaw

CVE-2025-47165 Overview

Use after free in Microsoft Office Excel allows an unauthorized attacker to execute code locally.

Critical Impact
A local attacker can exploit this vulnerability to execute arbitrary code, leading to potential data compromise and system control.

Affected Products

Microsoft 365 Apps
Microsoft Excel
Microsoft Office

Discovery Timeline

Not Available - Vulnerability discovered by Not Available
Not Available - Responsible disclosure to Microsoft
Not Available - CVE-2025-47165 assigned
Not Available - Microsoft releases security patch
2025-06-10 - CVE-2025-47165 published to NVD
2025-07-09 - Last updated in NVD database

Technical Details for CVE-2025-47165

Vulnerability Analysis

This vulnerability in Microsoft Office Excel arises due to a use-after-free condition during the processing of Excel files. When a specific sequence of operations is performed, a freed memory object may be re-used, allowing for arbitrary code execution.

Root Cause

The vulnerability is caused by improper management of memory objects, leading to the re-use of a freed object, which results in undefined behavior and potential code execution.

Attack Vector

Local

cpp

// Example exploitation code (sanitized)
#include <iostream>
int main() {
    char *ptr = new char[10];
    delete[] ptr;
    // Improper memory management allowing use-after-free
    strcpy(ptr, "exploit");
    std::cout << ptr << std::endl;
    return 0;
}

Detection Methods for CVE-2025-47165

Indicators of Compromise

Unexpected application crashes in Excel
Unusual file writes in user directories
Unauthorized changes in Excel documents

Detection Strategies

Utilize behavior-based detection mechanisms to identify anomalies in Excel processes, focusing on memory management errors and unusual process behaviors.

Monitoring Recommendations

Implement advanced endpoint detection to monitor Excel activity, using heuristics to flag memory misuse patterns or unauthorized execution flows.

How to Mitigate CVE-2025-47165

Immediate Actions Required

Apply the latest security patch from Microsoft immediately.
Disable macros and external content in Excel by default.
Educate users on safe file handling practices.

Patch Information

Patch details and updates can be found in the Microsoft Security Response Center advisory.

Workarounds

Until the patch is applied, limit Excel's functionality by disabling active content and enforcing strict file execution policies.

bash

# Configuration example to disable macros
reg add HKCU\Software\Microsoft\Office\16.0\Excel\Security /v "VBAWarnings" /t REG_DWORD /d 4 /f