CVE-2026-69722 in Office
Summary
by MITRE • 09/08/2026
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 • 09/08/2026
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 call stack. In the context of Microsoft Office Word, this often involves malformed documents, embedded objects, or specific file formats that trigger an incorrect memory allocation routine during parsing or rendering processes. When an attacker crafts a malicious document containing data exceeding the allocated buffer size, the excess data overwrites adjacent memory locations on the stack, potentially including critical control structures such as return addresses and saved frame pointers.
From a technical perspective, this flaw aligns with Common Weakness Enumeration (CWE) category CWE-121, which defines stack-based buffer overflow. The exploitation mechanism typically involves an attacker constructing a specially crafted file that, when opened by the victim using Word, causes the application to write data beyond the bounds of the intended memory region. By carefully controlling the content written into the overwritten memory space, the attacker can manipulate the execution flow of the program. This manipulation allows for arbitrary code execution, where the malicious payload runs with the same privileges as the user currently running the Office application. The network vector indicates that this exploit does not require physical access to the machine; instead, it can be delivered through email attachments, shared network drives, or web-based document repositories, significantly increasing the attack surface and ease of exploitation for threat actors.
The operational impact of successfully exploiting this vulnerability is severe, as it grants an unauthorized attacker full control over the affected system within the context of the logged-in user. This level of access enables a wide range of malicious activities including data theft, installation of malware such as keyloggers or ransomware, and using the compromised machine as a pivot point for further attacks against other systems on the internal network. Because Microsoft Office is ubiquitous in enterprise environments, this vulnerability poses a significant risk to organizational security posture. Attackers can leverage automated worm-like propagation mechanisms if the exploit is integrated into malicious documents distributed via spam campaigns or phishing emails, leading to rapid lateral movement and widespread compromise across an organization's infrastructure without requiring additional social engineering tactics beyond initial delivery.
Mitigation strategies for this vulnerability primarily involve applying vendor-provided security patches that address the underlying memory management errors within the Word application codebase. Organizations should prioritize immediate deployment of these updates on all endpoints running vulnerable versions of Microsoft Office to close the exploitation vector. In addition to patching, defense-in-depth measures are recommended to reduce risk. These include configuring Application Control policies such as Windows Defender Application Control or AppLocker to restrict the execution of untrusted scripts and binaries from temporary directories where downloaded documents often reside. Furthermore, enabling Protected View for files originating from the internet can isolate potentially malicious content in a sandboxed environment, preventing direct interaction with system resources until the file is explicitly trusted by the user. Regular security awareness training should also be implemented to educate employees on recognizing suspicious attachments and avoiding opening unexpected Office documents, thereby reducing the likelihood of successful initial exploitation through social engineering tactics aligned with MITRE ATT&CK techniques such as T1566 Phishing or T1059 Command and Scripting Interpreter if subsequent stages are attempted.