CVE-2026-88202 in Office Word
Summary
by MITRE • 10/14/2026
Heap-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 • 10/14/2026
The vulnerability described constitutes a critical security flaw within the Microsoft Office Word application, specifically manifesting as a heap-based buffer overflow condition. This type of memory corruption error occurs when a program writes data beyond the allocated boundaries of a buffer located in the computer's random access memory, known as the heap. In the context of Microsoft Office Word, this defect is triggered by processing specially crafted documents or content that exploits improper bounds checking during the parsing and rendering of file structures. The attacker leverages this flaw to overwrite adjacent memory locations with malicious data, which can include shellcode designed to execute arbitrary commands on the victim's system. Because heap overflows are often more complex to exploit than stack-based ones due to modern mitigations like Address Space Layout Randomization, their successful exploitation typically indicates a high level of sophistication in the attack vector and suggests that the vulnerability is being actively targeted by threat actors for remote code execution purposes.
The operational impact of this vulnerability is severe because it allows an unauthorized attacker to execute arbitrary code over a network without requiring any user interaction beyond opening or viewing the malicious document, depending on the specific configuration and version of Office involved. This capability effectively grants the attacker full control over the affected system, enabling them to install programs, view, change, or delete data, or create new accounts with full user rights. If the current user is logged in with administrative privileges, the impact is even more catastrophic as the attacker can compromise the entire infrastructure connected to that machine. The network-based nature of this exploit means it does not require physical access and can be delivered via email attachments, shared drives, or web-hosted documents, making it a significant threat for organizations relying on Microsoft Office for daily operations.
From a classification perspective, this vulnerability aligns with Common Weakness Enumeration identifier CWE-120, which describes buffer copy without checking size limits, specifically in the context of heap memory allocation failures. The exploitation technique maps directly to MITRE ATT&CK techniques related to remote code execution and injection attacks, particularly those involving client-side application vulnerabilities such as Client-Side Injection or Exploitation for Privilege Escalation if local elevation is achieved. Understanding these mappings helps security teams prioritize patching efforts based on established industry standards that categorize the severity and type of memory corruption flaws. The presence of this flaw indicates a failure in input validation routines within the Word application's core processing engine, where user-supplied data from document files was not adequately sanitized or length-checked before being copied into fixed-size heap buffers.
To mitigate the risks associated with this vulnerability, organizations must ensure that all Microsoft Office installations are updated to the latest security patches released by Microsoft. Immediate deployment of these updates is critical as they contain code changes that enforce stricter bounds checking and improve memory management practices within the application. In environments where immediate patching is not feasible due to compatibility concerns or operational constraints, network-level controls should be implemented to restrict access to untrusted documents. This includes configuring email gateways to strip potentially dangerous file attachments, implementing sandboxing solutions to analyze documents in isolated environments before they reach end-user devices, and applying application whitelisting policies to prevent the execution of unauthorized binaries that may result from a successful exploit. Regular vulnerability scanning and penetration testing should also be conducted to identify any instances where legacy versions of Office remain unpatched within the corporate network infrastructure.