CVE-2026-108445 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 involving a stack-based buffer overflow condition that can be triggered remotely via network interactions. This type of vulnerability arises when a program writes more data to a fixed-length block of memory on the call stack than it is allocated to hold. In the context of Microsoft Office Word, this typically occurs during the parsing or rendering of specific document formats, such as .docx files containing specially crafted content like embedded objects, complex formulas, or malformed metadata structures. When an attacker crafts a malicious file designed to exploit this flaw and distributes it through network channels such as email attachments, shared drives, or web downloads, they can cause the application to overwrite adjacent memory locations on the stack with arbitrary data. This overwriting often targets critical control flow elements like return addresses or function pointers, allowing the attacker to redirect the execution flow of the compromised process.
From a technical perspective, this flaw aligns closely with Common Weakness Enumeration (CWE) identifiers such as CWE-120 Buffer Copy without Checking Size of Input and CWE-787 Out-of-bounds Write on Stack. The exploitation mechanism relies on precise memory layout manipulation to achieve arbitrary code execution. By controlling the data written into the buffer, an attacker can inject shellcode or leverage existing executable modules within the system environment through techniques like Return Oriented Programming (ROP). This capability effectively bypasses standard security controls that rely on preventing direct injection of malicious instructions, as ROP chains utilize legitimate code snippets already present in memory. The vulnerability is particularly severe because it does not require user interaction beyond opening the file, and if Word is configured to open files automatically or if preview panes are enabled, the attack can be executed with minimal effort from the victim.
The operational impact of this vulnerability is profound, as successful exploitation grants an unauthorized attacker full control over the affected system under the context of the currently logged-in user. This level of access allows for a wide range of malicious activities including data theft, installation of backdoors, deployment of ransomware, or using the compromised machine as a pivot point to attack other systems within the network. The ability to execute code remotely makes this vulnerability highly attractive in automated worm propagation scenarios where attackers scan networks for vulnerable instances and exploit them without any direct contact with end-users. Furthermore, because Microsoft Office is ubiquitous across enterprise environments, the potential blast radius of such an exploitation can be extensive, affecting critical business operations and sensitive data repositories stored on or accessible from compromised endpoints.
In terms of threat intelligence frameworks, this vulnerability maps to MITRE ATT&CK techniques related to Initial Access via Spearphishing Attachment (T1566) and Execution via User Interface (T1204), specifically the component involving malicious documents. The exploitation path often involves social engineering tactics combined with technical payload delivery through network vectors. Defense strategies must therefore focus on both technical controls and user awareness. Immediate mitigation requires applying vendor-supplied security patches that address the memory handling logic within Word to prevent buffer overflows from occurring during document processing. Additionally, organizations should implement application whitelisting policies to restrict the execution of untrusted scripts or binaries spawned by Office applications, thereby limiting the impact even if an exploit succeeds. Network segmentation and strict email filtering rules can also reduce the attack surface by blocking suspicious attachments before they reach end-user devices. Regular vulnerability scanning and patch management cycles are essential to ensure that known flaws like this one do not remain exploitable in production environments for extended periods.