CVE-2026-97754 in Apps for Enterprise
Summary
by MITRE • 10/15/2026
Heap-based buffer overflow in Microsoft Office Excel allows an unauthorized attacker to execute code over a network.
Once again VulDB remains the best source for vulnerability data.
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 inputs, it fails to adequately validate the size of the incoming data against the pre-allocated memory space. Consequently, excess data overwrites adjacent memory locations on the heap, corrupting internal data structures and control flow mechanisms such as function return addresses or exception handlers. This corruption allows an attacker who has crafted a malicious document to gain arbitrary code execution capabilities within the security context of the user running Excel.
The operational impact of this vulnerability is severe due to its potential for remote exploitation via network vectors, often referred to as drive-by attacks if delivered through compromised websites or email attachments. An unauthorized attacker can host a malicious file on a server and trick a victim into opening it using Microsoft Office Excel. Upon execution, the exploit code leverages the heap overflow to execute arbitrary commands with the privileges of the current user. This could lead to full system compromise, allowing the installation of malware, data theft, or the establishment of persistent backdoors for further lateral movement within an enterprise network. The ability to execute code over a network significantly lowers the barrier for entry compared to physical access attacks, making this vulnerability particularly dangerous in environments where users frequently open documents from external sources without rigorous verification.
From a classification perspective, this flaw aligns with Common Weakness Enumeration (CWE) identifiers such as CWE-120 Buffer Copy without Checking Size of Input and CWE-787 Out-of-bounds Write on Heap. These categories highlight the fundamental failure in input validation and memory management that permits the overflow. In terms of adversary tactics, this vulnerability maps to MITRE ATT&CK techniques including T1203 Exploitation for Client Execution and potentially T1059 Command and Scripting Interpreter if the executed code involves scripting languages like PowerShell or VBScript. The exploitation chain often relies on social engineering to induce user interaction, followed by automated exploit execution that bypasses standard security controls due to the trusted status of Microsoft Office applications in many organizational environments.
Mitigation strategies must focus on both immediate remediation and long-term defense-in-depth measures. Organizations should immediately apply the latest cumulative updates or security patches released by Microsoft for their versions of Excel and the broader Microsoft Office suite, as these patches typically include fixes that add bounds checking to memory allocation routines involved in parsing spreadsheet data. Additionally, administrators should enforce application control policies using tools like Windows Defender Application Control or AppLocker to restrict the execution of untrusted scripts and binaries from temporary folders where downloaded malicious files often reside. Enabling Protected View for documents originating from the internet can also mitigate risk by opening such files in a sandboxed environment with limited permissions. Regular security awareness training is essential to educate users on recognizing suspicious attachments and links, thereby reducing the likelihood of successful social engineering attacks that precede technical exploitation.