A new vulnerability, CVE-2025-26629, has been discovered in Microsoft Office that could potentially allow an attacker to execute malicious code on the target system. In this comprehensive analysis, we will explore the details of this "Use After Free" vulnerability, how it can be exploited, and ways to protect your system from such attacks.

Exploit Details

CVE-2025-26629 is a "Use After Free" vulnerability found in Microsoft Office. A "Use After Free" vulnerability refers to a situation where the program frees a section of memory, but continues to use it, leading to unpredictable results, including data corruption or code execution. In this case, an attacker can exploit this vulnerability by crafting a malicious Office document, which, when opened by an unsuspecting victim, may execute arbitrary code on the victim's system.

The code snippet below demonstrates a simple example of a "Use After Free" vulnerability in C++

#include<iostream>
#include<cstdlib>

int main() {
  int* ptr = new int[10]; // Allocate and use memory
  *ptr = 42; 
  int* savedPtr = ptr;

  delete[] ptr; // Free memory
  ptr = NULL;

  std::cout << *savedPtr << std::endl; // Use after free
  return ;
}

In the example above, the memory is allocated and then freed. However, the pointer savedPtr continues to point to and use this memory, leading to unpredictable behavior and the potential for exploitation.

1. Link to the Original CVE-2025-26629 Advisory: https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2025-26629
2. Link to the Microsoft Security Update Guide: https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2025-26629

A plausible attack scenario involving CVE-2025-26629 could occur as follows

1. An attacker creates a malicious Office document, embedding malicious code that exploits CVE-2025-26629.
2. The attacker sends the document to the victim, typically in the form of a phishing email or a downloadable file from a compromised website.

The unsuspecting victim opens the document.

4. The malicious code embedded in the document exploits the "Use After Free" vulnerability, executing arbitrary code on the victim's system.
5. The attacker gains unauthorized access to the victim's system and can now perform a wide range of malicious activities, including data theft, ransomware infection, or even a complete system takeover.

To protect your system from threats like CVE-2025-26629, follow these best practices

1. Update your software: Always keep your software up-to-date, including Microsoft Office and your operating system. Regularly check for and install security updates and patches.
2. Use antivirus software: Use comprehensive and up-to-date antivirus software that can detect and block threats like the CVE-2025-26629 exploit.
3. Be cautious with email attachments: Don't open unexpected email attachments or download files from untrusted sources. Be especially careful with Office documents received from unknown senders.
4. Disable macros: Disable macros in Microsoft Office by default and only enable them for trusted documents.
5. Educate yourself and your employees: Learn about common tactics used by attackers, such as phishing attacks and social engineering, and how to recognize and avoid them.

Conclusion

CVE-2025-26629 is a serious vulnerability that could allow attackers to execute code on your system without authorization. By understanding how such exploits work and following best practices for security, you can minimize the risk of falling prey to such attacks. Always stay vigilant and keep your software updated to ensure the highest level of protection for your systems and data.

Timeline

Published on: 03/11/2025 17:16:39 UTC
Last modified on: 03/23/2025 16:12:32 UTC