CVE-2026-108431 in Office
Summary
by MITRE • 10/16/2026
Stack-based buffer overflow in Microsoft Office Word allows an unauthorized attacker to execute code over a network.
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Analysis
by VulDB Data Team • 10/16/2026
The vulnerability described constitutes a critical security flaw within the Microsoft Office Word application, specifically manifesting as a stack-based buffer overflow condition that can be exploited remotely via a network connection. This type of vulnerability arises when the software fails to properly validate the length or boundaries of user-supplied input before copying it into a fixed-size buffer located on the program's call stack. In the context of Microsoft Office Word, this often involves malformed documents or embedded objects where specific fields exceed their allocated memory space. When an attacker crafts a malicious document containing data that exceeds the expected buffer size and sends it to a victim over a network, such as through email attachments or shared file systems, the excess data spills over into adjacent memory locations on the stack. This overflow can overwrite critical control data, including return addresses and saved frame pointers, which are essential for maintaining the integrity of program execution flow.
The operational impact of this vulnerability is severe, allowing an unauthorized attacker to achieve arbitrary code execution with the privileges of the currently logged-in user. By carefully crafting the payload within the buffer overflow, an attacker can redirect the instruction pointer to execute shellcode or other malicious instructions injected into the memory space. This capability effectively grants the attacker full control over the affected system, enabling them to install malware, steal sensitive data, create new accounts with administrative privileges, or use the compromised machine as a pivot point for further attacks within the network infrastructure. The remote nature of this exploit means that exploitation can occur without any physical access to the target device, relying solely on the victim opening the malicious document in an affected version of Microsoft Office Word.
From a classification perspective, this vulnerability aligns with Common Weakness Enumeration (CWE) identifiers such as CWE-120 Buffer Copy without Checking Size of Input and CWE-787 Out-of-bounds Write to Stack. These categories highlight the fundamental failure in input validation and memory management that characterizes stack-based buffer overflows. Furthermore, within the MITRE ATT&CK framework, this exploitation technique maps directly to Tactic TA0002 Execution and specifically Technique T1059 Command and Scripting Interpreter or potentially T1203 Exploitation for Client Execution if delivered via a malicious document. The attack vector is classified as Network (Attack Vector: NETWORK), indicating that the vulnerability can be exploited from across a network boundary, provided the target application processes untrusted input without adequate sanitization checks.
Mitigation strategies must focus on both immediate remediation and long-term architectural improvements. Organizations should immediately apply vendor-provided security patches to update Microsoft Office Word to versions where this buffer overflow has been corrected through improved bounds checking and memory management routines. Additionally, implementing strict email filtering policies that block or quarantine documents from unknown senders can reduce the attack surface. Users must be educated on social engineering tactics often used in conjunction with such exploits, as attackers frequently rely on deceiving users into opening seemingly legitimate but maliciously crafted files. Enabling Protected View for all Office documents opened from potentially unsafe locations adds an extra layer of defense by isolating the document processing environment and preventing automatic execution of active content until the user explicitly trusts the source.