CVE-2025-53732: Critical Heap-based Buffer Overflow Vulnerability in Microsoft Office

Overview

The Common Vulnerabilities and Exposures (CVE) system has recently identified a critical vulnerability, CVE-2025-53732, that poses a significant risk to users of Microsoft Office. This vulnerability, a heap-based buffer overflow, can be exploited by unauthorized attackers to execute code locally, potentially leading to system compromise or data leakage. Given the widespread usage of Microsoft Office across industries and sectors, understanding and addressing this vulnerability is of paramount importance for organizations and individuals alike.

Vulnerability Summary

CVE ID: CVE-2025-53732
Severity: High (7.8 CVSS Score)
Attack Vector: Local
Privileges Required: None
User Interaction: Required
Impact: System compromise or data leakage

Affected Products

Product | Affected Versions

Microsoft Office | All versions until patched

How the Exploit Works

This vulnerability exploits a heap-based buffer overflow in Microsoft Office. Essentially, the attacker overflows the application’s buffer memory with more data than it can hold. The extra data then spills over into adjacent memory locations, corrupting or even overwriting the valid data held in them. If the attacker can control the data that overflows the buffer, they can manipulate the execution path of the program, leading to arbitrary code execution.

Conceptual Example Code

While actual exploit code will vary greatly depending on the specific buffer overflow and the attacker’s goals, below is a simplistic, conceptual example of how a buffer overflow might be triggered.

#include <string.h>
void vulnerable_function(char *input) {
char buffer[50];
strcpy(buffer, input);
}
int main() {
char malicious_input[100];
for (int i=0; i<100; i++)
malicious_input[i] = 'A';
vulnerable_function(malicious_input);
return 0;
}

In this example, the `vulnerable_function` is designed to copy an input string into a buffer of size 50. However, if the input string is longer than what the buffer can hold, like the `malicious_input` of 100 ‘A’s, a buffer overflow occurs. This can potentially lead to arbitrary code execution, with the specific effects dependent on the context and the attacker’s goals.

Mitigation

The best mitigation for this vulnerability is to apply the patch provided by the vendor as soon as it is available. Until then, a Web Application Firewall (WAF) or Intrusion Detection System (IDS) can be used as a temporary measure to detect and block exploitation attempts. However, these measures only provide a stop-gap solution and do not eliminate the vulnerability, so applying the vendor’s patch should be a priority.