CVE-2025-30377: Code Execution Vulnerability in Microsoft Office via Use After Free

Overview

The Common Vulnerabilities and Exposures (CVE) system has identified a significant vulnerability, classified as CVE-2025-30377, in Microsoft Office. This vulnerability, if left unaddressed, could allow unauthorized attackers to execute code locally on affected systems. Given the widespread use of Microsoft Office in both personal and corporate settings worldwide, this vulnerability carries a high risk, potentially leading to system compromise or data leakage.

Vulnerability Summary

CVE ID: CVE-2025-30377
Severity: High (8.4/10)
Attack Vector: Local
Privileges Required: None
User Interaction: Required
Impact: Unauthorized code execution leading to potential system compromise or data leakage

Affected Products

Product | Affected Versions

Microsoft Office | All versions prior to the latest patch

How the Exploit Works

This vulnerability takes advantage of a ‘use after free’ flaw existing in Microsoft Office. A ‘use after free’ vulnerability refers to the attempt to access memory after it has been freed, which can lead to a variety of adverse impacts including program crashes, incorrect data processing, and potentially, the execution of harmful code. In this case, an attacker could exploit the vulnerability by crafting a special Microsoft Office file that, when opened, triggers the ‘use after free’ condition and allows the attacker to execute arbitrary code in the context of the current user.

Conceptual Example Code

Below is a conceptual example of how the vulnerability might be exploited:

# A PowerShell script that crafts a malicious Office document
$filePath = "path\to\malicious.docx"
$payload = "arbitrary code here"
# Open the file and write the payload
$file = [System.IO.File]::OpenWrite($filePath)
$writer = New-Object System.IO.StreamWriter($file)
$writer.Write($payload)
$writer.Close()
$file.Close()
# Send the file to the target user
Send-MailMessage -To "target@example.com" -From "attacker@example.com" -Subject "Important Document" -Body "Please open the attached document." -Attachments $filePath -SmtpServer "smtp.example.com"

This script creates a malicious Office document containing arbitrary code and sends it to a target user. If the user opens the document, the code will execute, exploiting the vulnerability.

Mitigation Guidance

The best defense against this vulnerability is to apply the latest vendor patches from Microsoft for Microsoft Office. This will ensure that the ‘use after free’ flaw is effectively patched and can no longer be exploited. In the absence of a patch, implementing a Web Application Firewall (WAF) or Intrusion Detection System (IDS) may serve as a temporary mitigation measure. However, these should not be considered long-term solutions as they may not fully protect against the vulnerability. Regular system updates and patching remain the most effective defense.