Overview

The CVE-2025-54900 vulnerability is a serious security flaw found in Microsoft Office Excel, which potentially allows an unauthorized attacker to execute arbitrary code on a victim’s system. This vulnerability poses a significant threat to any user of the affected Microsoft Office Excel versions due to its high severity score and potential for system compromise or data leakage.

Vulnerability Summary

CVE ID: CVE-2025-54900
Severity: High (7.8 CVSS Score)
Attack Vector: Local
Privileges Required: None
User Interaction: Required
Impact: Unauthorized code execution, potential for system compromise and data leakage

Affected Products

Product | Affected Versions

Microsoft Office Excel | All versions prior to vendor patch

How the Exploit Works

The vulnerability is a heap-based buffer overflow, which occurs when Microsoft Office Excel improperly handles objects in memory. An attacker can exploit this flaw by convincing a user to open a specially crafted Excel file, causing the application to overflow its buffer. This overflow can corrupt data, crash the application, and, in this case, allow the attacker to execute arbitrary code.

Conceptual Example Code

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

File maliciousFile = new ExcelFile("malicious.xlsx");
Buffer buffer = new Buffer();
byte[] maliciousPayload = getMaliciousPayload(); // Acquired from an attack command and control server
// Fill the buffer with more data than it can handle
for (int i = 0; i < buffer.size + 1; i++) {
buffer.write(maliciousPayload[i]);
}
// Save the overflowed buffer into the file
maliciousFile.save(buffer);

In this pseudocode, the `maliciousPayload` is written into the buffer space of the Excel file, causing an overflow. This overflow can then be used to execute the malicious payload, leading to arbitrary code execution.