CVE-2026-97003 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 containing specially crafted formulas, embedded objects, or specific formatting structures that trigger incorrect memory allocation calculations. When an attacker crafts a malicious document designed to exploit these parsing routines, they can overwrite adjacent memory locations with arbitrary data, thereby gaining control over the program's execution flow.
The operational impact of this vulnerability is severe due to its potential for remote code execution without user interaction beyond opening the file. An unauthorized attacker who successfully exploits this flaw can execute arbitrary code on the target system under the context of the current user privileges. This capability allows the adversary to install programs, view, change, or delete data, and create new accounts with full user rights. If the affected user is logged on with administrative privileges, an attacker could gain complete control over the compromised computer, facilitating further lateral movement within a network environment. The risk is amplified by the ubiquity of Microsoft Office products in enterprise environments, making them frequent targets for phishing campaigns and spear-phishing attacks that rely on social engineering to deliver malicious Excel files via email or shared drives.
From a technical classification perspective, this vulnerability aligns with CWE-120, which denotes Buffer Copy without Checking Size of Input Classic Heap-based Overflow. The exploitation mechanism often involves manipulating the heap metadata or function pointers stored within the memory space allocated for Excel's internal data structures. By carefully crafting the input to overflow the buffer, an attacker can achieve arbitrary code execution by redirecting program control flow to shellcode injected into the process memory. This aligns with MITRE ATT&CK technique T1203, which covers Exploitation for Client Execution, where attackers leverage vulnerabilities in client software to gain initial access and establish a foothold on the target system.
Mitigation strategies must focus on both preventive controls and reactive measures. Organizations should ensure that Microsoft Office applications are kept up-to-date with the latest security patches released by Microsoft, as these updates typically include fixes for such memory corruption issues. Implementing application whitelisting can prevent unauthorized or untrusted scripts from running, thereby reducing the impact of successful exploitation. Additionally, deploying advanced email gateways and endpoint detection and response solutions that analyze file behavior and detect anomalous activities associated with exploit attempts is crucial. Users should be trained to exercise caution when opening files received from unknown sources, particularly those containing macros or complex formulas, as these are common vectors for delivering exploits targeting this specific vulnerability class.