CVE-2026-63531 in Office
Summary
by MITRE • 08/11/2026
Out-of-bounds read in Microsoft Office Word allows an unauthorized attacker to disclose information locally.
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Analysis
by VulDB Data Team • 08/11/2026
This vulnerability represents a critical out-of-bounds read flaw within Microsoft Office Word that enables unauthorized attackers to extract sensitive information from the targeted system. The vulnerability stems from insufficient input validation and memory management within the word processing application's parsing mechanisms, particularly when handling malformed or specially crafted document structures. Attackers can exploit this weakness by preparing malicious documents that trigger buffer over-read conditions during document rendering or processing operations, allowing them to access memory regions beyond the intended boundaries of allocated buffers.
The technical execution of this vulnerability typically involves crafting specific document formats or content that causes Word's internal parsers to read data from memory locations that should remain protected or inaccessible. This occurs when the application fails to properly validate array indices or buffer limits during document parsing operations, particularly in features related to table handling, formatting structures, or embedded object processing. The flaw manifests as an unauthorized information disclosure mechanism where attackers can potentially extract sensitive data such as memory contents, cryptographic keys, or other confidential information from the application's memory space.
From an operational perspective, this vulnerability poses significant risks to organizations relying on Microsoft Office Word for document processing and collaboration. The local information disclosure aspect means that successful exploitation requires minimal privileges and can occur when users open malicious documents within the Word application environment. Attackers may leverage this vulnerability as part of broader attack chains, potentially combining it with other exploits or social engineering techniques to achieve more comprehensive system compromise. The impact extends beyond simple data theft since memory contents often contain sensitive information that could be used for further exploitation attempts.
Security mitigation strategies should focus on immediate patch management through Microsoft's regular security updates and cumulative releases. Organizations must implement strict document validation policies and consider deploying application whitelisting solutions to prevent execution of untrusted Office documents. Network-based protections such as email filtering and sandboxing mechanisms can provide additional layers of defense against exploitation attempts. The vulnerability aligns with CWE-125 Out-of-bounds Read classification and may map to ATT&CK technique T1059 Command and Scripting Interpreter for executing malicious code, while also supporting T1074 Data Staged for lateral movement through information gathering activities. Regular security awareness training for users regarding suspicious document attachments remains essential in preventing successful exploitation attempts through social engineering vectors.