CVE-2026-108449 in 365 Apps for Enterprise
Summary
by MITRE • 10/16/2026
Heap-based buffer overflow in Microsoft Office Word allows an unauthorized attacker to execute code over a network.
Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.
Analysis
by VulDB Data Team • 10/16/2026
The vulnerability described constitutes a critical security flaw within the document processing engine of Microsoft Office Word, specifically manifesting as a heap-based buffer overflow condition. This type of memory corruption error occurs when data is written beyond the allocated boundaries of a buffer located in the computer's random access memory (RAM). In the context of Microsoft Office applications, this typically involves the parsing and rendering of complex document structures or embedded objects where input validation mechanisms fail to adequately check the size of incoming data against the pre-allocated heap space. When an attacker crafts a malicious Word document containing specially formatted content that exceeds expected limits, the application attempts to write this oversized payload into the buffer without proper bounds checking. This action overwrites adjacent memory locations on the heap, corrupting internal data structures and control flow mechanisms such as function return addresses or pointer values used by the application's runtime environment.
The operational impact of this vulnerability is severe due to its potential for remote code execution with no user interaction beyond opening the document in certain configurations, although typically it requires the victim to open a maliciously crafted file. An unauthorized attacker can exploit this flaw to execute arbitrary commands on the target system under the context of the current user privileges. This capability allows for full compromise of the affected workstation or server, enabling data exfiltration, installation of additional malware such as backdoors or ransomware, and lateral movement within a corporate network if the compromised machine serves as an entry point. The vulnerability is particularly dangerous because it targets widely deployed productivity software used across enterprise environments, making large-scale exploitation campaigns feasible through social engineering tactics like phishing emails containing malicious attachments.
From a classification perspective, this flaw 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 on Heap. These categories highlight the fundamental failure in input validation and memory management practices within the software development lifecycle that led to the defect. Furthermore, from a tactical standpoint related to the MITRE ATT&CK framework, this vulnerability facilitates initial access techniques involving spearphishing attachment or drive-by compromise if hosted online. The exploitation chain typically involves crafting a malicious document file that triggers the overflow during parsing, leading to code execution which may then be used to download and execute secondary payloads from remote command-and-control infrastructure.
Mitigation strategies for this vulnerability require immediate patching of all affected Microsoft Office installations with the latest security updates provided by Microsoft. Organizations should enforce strict email filtering policies to block or quarantine documents containing macros or embedded objects that are not explicitly trusted, as these vectors often facilitate the delivery of such exploits. Additionally, implementing application control solutions can prevent unauthorized executables from running even if exploitation occurs. Users must be educated on recognizing suspicious attachments and avoiding opening files from untrusted sources. Network segmentation and endpoint detection and response (EDR) tools should also be utilized to monitor for anomalous behavior indicative of exploit attempts or post-exploitation activities, thereby reducing the blast radius in case a vulnerability is successfully leveraged before patches are applied.