CVE-2026-97009 in Office
Summary
by MITRE • 10/14/2026
Heap-based buffer overflow in Microsoft Office Excel allows an unauthorized attacker to execute code locally.
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Analysis
by VulDB Data Team • 10/14/2026
The vulnerability described constitutes a heap-based buffer overflow within the Microsoft Office Excel application, representing a critical security flaw that can be leveraged by attackers to achieve arbitrary code execution on affected systems. This type of defect arises when a program writes data beyond the allocated boundaries of a buffer located in the heap memory segment, which is dynamically managed during runtime. In the context of Excel, this often occurs when processing specially crafted files or malformed input data that triggers an incorrect calculation of buffer sizes or fails to properly validate user-supplied content before copying it into pre-allocated memory regions. The exploitation of such vulnerabilities typically involves crafting a malicious document containing specific structures or formulas designed to overflow adjacent heap metadata or function pointers, thereby allowing the attacker to redirect program execution flow.
From a technical perspective, this vulnerability aligns with Common Weakness Enumeration (CWE) identifiers such as CWE-122, which denotes a heap-based buffer overflow, and potentially CWE-787 if it involves out-of-bounds writes that corrupt memory structures critical for application stability. The operational impact is severe because successful exploitation grants the attacker the same privileges as the current user running the Excel process. This can lead to full system compromise, including the installation of malware, theft of sensitive data stored locally or in connected cloud services, and lateral movement within a network if the compromised machine serves as an entry point for further attacks. The ability to execute code locally without authentication makes this particularly dangerous in enterprise environments where users frequently open documents from external sources or untrusted networks.
The attack vector is typically remote via email attachments or shared drives, falling under MITRE ATT&CK techniques such as T1204.002 (User Execution: Malicious File) and potentially T1059 if the executed code involves scripting components like VBA macros that are triggered by the overflow condition. Attackers often combine this vulnerability with social engineering tactics to persuade victims into opening malicious Excel files, thereby initiating the exploit chain. Once the heap corruption occurs, it may lead to control over critical data structures such as function pointers or exception handlers, allowing for shellcode injection and subsequent privilege escalation if additional vulnerabilities are present in the system stack.
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 to address known heap overflow issues. Implementing application whitelisting can prevent unauthorized scripts or executables from running, while disabling macros by default reduces the attack surface for document-based exploits. Additionally, deploying endpoint detection and response solutions capable of monitoring memory corruption events can help identify and block exploitation attempts in real time. Users should be trained to verify the source of incoming documents and avoid opening files with unexpected extensions or those originating from untrusted entities, thereby reducing the likelihood of triggering such vulnerabilities through social engineering vectors.