CVE-2025-30375: Type Confusion Vulnerability in Microsoft Office Excel Leading to Unauthorized Code Execution

Overview

Security vulnerabilities are a significant concern in the rapidly evolving world of technology. One such vulnerability that has come to light recently is the CVE-2025-30375. This particular vulnerability affects Microsoft Office Excel, a widely used spreadsheet program found in numerous businesses and industries around the globe. The threat lies in a type confusion error, allowing an unauthorized attacker to execute code locally. This vulnerability is not just a potential threat to the integrity of data but can also result in system compromise.

Vulnerability Summary

CVE ID: CVE-2025-30375
Severity: High (7.8 CVSS score)
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 Excel | All versions prior to the patch

How the Exploit Works

The exploit takes advantage of a type confusion error in Microsoft Office Excel. Type confusion, often also referred to as type casting, is an error that occurs when a piece of code is not properly checking the type of an object that it is handling. In this case, an attacker can manipulate data that the software misinterprets, leading to an unexpected behavior. An attacker with knowledge of this vulnerability can craft a malicious Excel document, which, when opened by the victim, executes the attacker’s code.

Conceptual Example Code

Imagine an attacker creates a malicious Excel document with embedded VBA macro code. When the victim opens the document and enables macros (perhaps due to a convincing social engineering trick), the code runs.
Here is a simplified conceptual example of what the VBA macro code might look like:

Sub Auto_Open()
Dim buffer As String
buffer = Space(1024) ' Create a string with 1024 spaces
CopyMemory ByVal VarPtr(buffer), ByVal &H12345678, 4 ' Copy data to buffer causing type confusion
Execute(buffer) ' Execute the malicious code
End Sub

Remember, this is just a conceptual example and the actual exploit code would be more complex and specific to the vulnerable application’s internals.

Mitigation Guidance

To mitigate the risk associated with this vulnerability, users are advised to apply the vendor-issued patch as soon as it becomes available. Until then, users can use a Web Application Firewall (WAF) or an Intrusion Detection System (IDS) as a temporary mitigation strategy. Always be wary of unsolicited documents and do not enable macros unless it is absolutely necessary and the source is trusted.