CVE-2026-97768 in Office
Summary
by MITRE • 10/15/2026
Heap-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 heap-based buffer overflow. This type of memory corruption error occurs when a program writes data beyond the allocated boundaries of a buffer located in the heap segment of computer memory. In the context of Excel, this typically involves the processing of complex or malformed spreadsheet files that contain specially crafted objects, formulas, or embedded content. When the application attempts to parse these malicious inputs, it fails to properly validate the size of the data against the allocated memory space, leading to an overwrite of adjacent memory structures. This overwriting can corrupt critical control flow data such as function return addresses or exception handlers, which are essential for normal program execution.
The operational impact of this vulnerability is severe due to its potential for remote code execution without user interaction beyond opening a malicious file. An attacker can host the exploit on a web server and use social engineering techniques to lure users into viewing a specially crafted Excel document via Microsoft Office Web Apps or by simply attaching it in an email. Once the victim opens the file, the vulnerability is triggered during the parsing phase of the application's engine. Because heap-based overflows allow for precise memory manipulation, attackers can often achieve arbitrary code execution with the privileges of the current user. This means that if a system administrator or privileged user falls victim to this attack, the attacker gains full control over the affected machine, potentially leading to data theft, installation of malware, or use as part of a botnet.
From an industry standards perspective, this vulnerability aligns closely with CWE-122: Heap-based Buffer Overflow, which categorizes errors where buffer operations are performed on heap memory without proper bounds checking. Furthermore, the exploitation vector and technique map directly to MITRE ATT&CK techniques such as T1059 Command and Scripting Interpreter for executing malicious code after initial access, or more specifically T1203 Exploitation for Client Execution if delivered via a lure file. The network-based nature of the attack highlights the risk associated with handling untrusted content from external sources within productivity software that is designed to process diverse data formats.
Mitigation strategies must focus on both technical controls and user awareness. Organizations should ensure that Microsoft Office applications are updated with the latest security patches released by Microsoft, as these updates typically include fixes for memory safety issues like buffer overflows. Additionally, implementing application whitelisting can prevent unauthorized scripts or executables from running after an initial compromise. Users must be trained to exercise caution when opening files received via email or downloaded from untrusted sources, particularly those with extensions associated with Office applications that may contain macros or embedded objects. Network segmentation and the use of advanced threat protection solutions that inspect file contents for malicious patterns can also reduce the likelihood of successful exploitation by detecting and blocking suspicious documents before they reach end-user devices.