CVE-2026-97750 in Office
Summary
by MITRE • 10/15/2026
Stack-based buffer overflow in Microsoft Office Excel allows an unauthorized attacker to execute code over a network.
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Analysis
by VulDB Data Team • 10/15/2026
The vulnerability described constitutes a critical security flaw within the Microsoft Office Excel application, specifically manifesting as a stack-based buffer overflow condition. This type of memory corruption error occurs when a program writes more data to a fixed-length block of memory allocated on the call stack than it is intended to hold. In the context of Excel, this typically arises during the processing of specially crafted files or input streams that contain malformed data structures. When the application attempts to process these inputs without adequate bounds checking, the excess data overwrites adjacent memory locations on the stack. This overwrite can corrupt critical control flow information, such as return addresses and saved frame pointers, which are essential for maintaining the integrity of program execution during function calls.
The operational impact of this vulnerability is severe due to its potential for remote code execution. Because Excel is frequently used to open documents received via email or downloaded from untrusted sources over a network, an attacker can exploit this flaw by tricking a user into opening a malicious file. Once the vulnerable component processes the crafted input, the overwritten stack data allows the attacker to redirect program execution flow. By carefully crafting the payload that fills the buffer and overwrites the return address, the attacker can inject shellcode or point execution to existing executable code within the application memory space. This results in arbitrary code execution with the privileges of the user running Excel, potentially leading full compromise of the affected system including data theft, installation of malware, or use as a pivot point for further network attacks.
From an industry standards perspective, this vulnerability aligns closely with Common Weakness Enumeration identifier CWE-121, which defines stack-based buffer overflow. The exploitation technique often involves manipulating memory layout to bypass modern mitigations such as Data Execution Prevention and Address Space Layout Randomization, although the effectiveness of these protections depends on specific system configurations and Excel versions. In terms of attack vectors, this scenario maps to MITRE ATT&CK techniques related to Initial Access via Spearphishing Attachment or Drive-by Compromise, where the malicious file serves as the initial vector for delivering exploit code into the target environment. The network-based nature of the delivery mechanism highlights the risk associated with trusting external inputs without rigorous validation and sanitization procedures at the application level.
Mitigation strategies must address both immediate remediation and long-term defensive posture. Organizations should immediately apply vendor-provided security patches that correct the memory handling logic within Excel to enforce strict bounds checking on all stack-allocated buffers. Administrators should also consider implementing Application Control policies, such as Microsoft AppLocker or Windows Defender Application Control, to restrict the execution of untrusted scripts and binaries from temporary folders where downloaded files are often stored. Additionally, enabling Enhanced Security Configuration for Office applications can limit macro execution and block potentially unsafe content by default. Users must be educated on social engineering tactics used in spearphishing campaigns that target Excel documents, as technical controls alone cannot prevent users from opening malicious attachments if they bypass security warnings. Regular vulnerability scanning and patch management cycles are essential to ensure that known flaws like this stack-based overflow remain closed against active exploitation attempts observed in the wild by threat actors seeking unauthorized access over networks.