CVE-2025-30379: Release of Invalid Pointer in Microsoft Office Excel Leading to Local Code Execution

Overview

The vulnerability under discussion, CVE-2025-30379, is a serious flaw found in Microsoft Office Excel that allows an unauthorized attacker to execute code locally. This vulnerability affects any user who utilizes Microsoft Office Excel, a widely used spreadsheet software. The severity of this vulnerability is high, not only because of its potential for system compromise and data leakage, but also due to the ubiquitous use of the affected software, making a vast number of systems worldwide potential targets.

Vulnerability Summary

CVE ID: CVE-2025-30379
Severity: High (CVSS Score 7.8)
Attack Vector: Local
Privileges Required: None
User Interaction: Required
Impact: Potential system compromise or data leakage

Affected Products

Product | Affected Versions

Microsoft Office Excel | All versions prior to the patch

How the Exploit Works

The vulnerability lies in the improper handling of memory objects by Microsoft Office Excel. When a specially crafted Excel file is opened, it triggers the release of an invalid pointer or reference. This can lead to undefined behavior, such as memory corruption or application crashes. However, a skilled attacker can manipulate this undefined behavior to execute arbitrary code in the context of the current user.
If the current user is logged in with administrative privileges, the attacker can take control of the affected system. This could potentially lead to system compromise, allowing the attacker to install programs, view, change, or delete data, or create new accounts with full user rights.

Conceptual Example Code

In this conceptual example, an attacker might embed malicious code in an Excel file that triggers the vulnerability when the file is opened. The code might look something like this:

Sub Workbook_Open()
Dim buffer As String
buffer = Space(4096) ' Create a large string.
Range("A1").Value = buffer ' Release the invalid pointer.
Shell "cmd.exe /c " & "malicious_command" ' Execute arbitrary code.
End Sub

This VBA (Visual Basic for Applications) code creates a large string that triggers the memory corruption when assigned to a cell (“A1”). The Shell function then executes arbitrary command-line instructions within the context of the current user.
Please note that this is a simplified and conceptual example. Actual exploits might involve more complex and obfuscated code.