CVE-2026-102867 in 365 Apps for Enterprise
Summary
by MITRE • 10/13/2026
Out-of-bounds read in Microsoft Office Word allows an unauthorized attacker to disclose information 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 document parsing engine of Microsoft Office Word, specifically manifesting as an out-of-bounds read condition. This type of memory corruption error occurs when the application attempts to access data at a memory location that is outside the boundaries of the intended buffer or array structure during the processing of a maliciously crafted Word document. The root cause typically lies in insufficient validation of input parameters, such as malformed metadata, embedded objects, or specific formatting codes within the .docx file format. When an attacker constructs a specially designed document containing these anomalous structures, they can manipulate the internal pointers used by the application to track memory offsets. Consequently, instead of halting execution upon detecting invalid access attempts, the software proceeds to read from adjacent memory regions that were not intended for public disclosure or external exposure.
From a technical perspective, this flaw aligns with Common Weakness Enumeration (CWE) identifiers such as CWE-125 Out-of-bounds Read and potentially CWE-20 Improper Input Validation if the root cause involves inadequate sanitization of user-supplied data before processing. The operational impact is primarily focused on information disclosure rather than immediate code execution or system compromise, although the severity depends heavily on the specific memory contents exposed at the time of exploitation. An unauthorized attacker who successfully exploits this vulnerability can leverage the resulting memory leak to extract sensitive data residing in the process space of the Word application. This may include cached credentials, session tokens, clipboard history, or other confidential information stored temporarily by Microsoft Office during document rendering and editing operations. The attack vector is typically remote via network delivery, often facilitated through social engineering tactics where a victim opens a maliciously crafted file received via email or downloaded from an untrusted source.
In the context of adversary behavior frameworks like MITRE ATT&CK, this vulnerability facilitates techniques associated with Collection and Credential Access, specifically under sub-techniques involving data from local system memory or clipboard capture. The attacker does not need to execute arbitrary code on the target machine but rather relies on the application's own processing logic to inadvertently reveal internal state information over a network connection if combined with other exploitation mechanisms or simply by analyzing the leaked data locally after opening the file. This makes detection challenging as standard antivirus signatures may not trigger, and the behavior mimics legitimate document loading activities until the memory access anomaly occurs.
Mitigation strategies for this vulnerability require immediate attention to patch management protocols within organizational IT infrastructure. Administrators should ensure that all affected versions of Microsoft Office are updated with the latest security patches released by Microsoft to address these specific parsing flaws in the Word engine. Beyond software updates, defense-in-depth measures such as enabling Protected View for documents opened from potentially unsafe locations can significantly reduce risk by isolating document processing in a sandboxed environment where memory access is restricted and monitored. Additionally, implementing application whitelisting policies and restricting macro execution unless explicitly trusted can further limit the attack surface available to adversaries attempting to exploit similar vulnerabilities through more complex exploitation chains that might combine this information leak with other techniques for persistent access or lateral movement.