CVE-2026-68813 in Office
Summary
by MITRE • 08/12/2026
Out-of-bounds read in Microsoft Office Excel allows an unauthorized attacker to disclose information locally.
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Analysis
by VulDB Data Team • 08/12/2026
This vulnerability represents a critical out-of-bounds read flaw in Microsoft Office Excel that enables local attackers to extract sensitive information from memory locations beyond the intended buffer boundaries. The technical implementation involves improper input validation within Excel's spreadsheet processing engine where array indexing operations fail to properly bounds-check user-supplied data structures. When parsing maliciously crafted Excel files or manipulating spreadsheet elements, the application attempts to access memory regions that contain confidential data such as encryption keys, authentication tokens, or system credentials stored in adjacent memory locations. This type of vulnerability falls under the common weakness enumeration CWE-125 which specifically addresses out-of-bounds read conditions that can lead to information disclosure and potential privilege escalation scenarios.
The operational impact of this vulnerability extends beyond simple information disclosure as it creates opportunities for attackers to gather intelligence about system configurations, user credentials, or application state information that could subsequently be leveraged in more sophisticated attacks. Attackers typically exploit this weakness by crafting specially formatted Excel documents containing malicious data structures designed to trigger the out-of-bounds read condition when opened or processed by vulnerable Excel versions. The attack vector operates locally since the vulnerability requires user interaction with a malicious file rather than remote exploitation, making it particularly dangerous in environments where users regularly open spreadsheet files from untrusted sources.
From an attack framework perspective, this vulnerability aligns with ATT&CK technique T1059.005 which involves execution through scripting languages and could potentially be combined with other techniques such as T1074 for data staging or T1566 for initial access through malicious documents. The exploitation process typically involves preparing a malicious Excel file that, when opened by an affected system, triggers the memory access violation and subsequently dumps sensitive information from adjacent memory locations into accessible buffers that can be read by the application. Organizations should consider implementing application whitelisting policies and restricting user permissions to limit potential damage from such attacks.
Mitigation strategies include applying Microsoft's security patches promptly through regular update management processes, implementing strict file validation procedures for spreadsheet documents, and deploying endpoint protection solutions that can detect and block malicious Excel file patterns. Network segmentation and user education regarding the dangers of opening unknown spreadsheet files can also reduce the attack surface. Additionally, system administrators should monitor for unusual memory access patterns or unauthorized file processing activities that might indicate exploitation attempts. The vulnerability underscores the importance of proper input validation and bounds checking in software development practices, particularly for applications handling complex data formats like Microsoft Office documents. Organizations should also consider implementing automated threat hunting procedures to identify potential exploitation attempts and maintain detailed audit logs of spreadsheet file processing activities for forensic analysis purposes.