CVE-2026-97748 in Office
Summary
by MITRE • 10/14/2026
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 • 10/14/2026
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 computer's random access memory (RAM). In the context of Excel, this typically involves the processing of complex or malformed spreadsheet files that contain specially crafted formulas, embedded objects, or structured storage elements designed to exploit parsing logic errors. When an attacker crafts a malicious document with specific data structures intended to trigger these overflow conditions, they can overwrite adjacent memory locations on the heap, potentially gaining control over critical execution pointers such as function return addresses or exception handlers.
From a technical perspective, this vulnerability aligns closely with Common Weakness Enumeration (CWE) identifiers including CWE-122 for Heap-based Buffer Overflow and often intersects with CWE-787 regarding out-of-bounds writes in heap memory operations. The exploitation mechanism relies on the application's failure to adequately validate input data lengths before copying them into fixed-size buffers during file parsing or rendering processes. By carefully crafting the payload, an attacker can manipulate the program flow to execute arbitrary code within the security context of the currently logged-in user. This is particularly dangerous because it does not require any special privileges on the target system beyond having a standard user account with access to run applications like Excel.
The operational impact of this vulnerability is severe due to its network-vector capability, which classifies it under MITRE ATT&CK technique T1566.002 for Spearphishing Attachment. An attacker can distribute the malicious file through various channels such as email attachments, shared network drives, or web downloads. Once a victim opens the compromised Excel file, the exploit code executes automatically without requiring further interaction from the user in many scenarios. This allows the adversary to achieve remote code execution (RCE), leading to full system compromise if the application runs with elevated privileges or if subsequent exploitation steps are chained together. The attacker can install malware, steal sensitive data, create backdoors for persistent access, or use the compromised machine as a pivot point for lateral movement within an enterprise network.
Mitigation strategies must focus on both immediate remediation and long-term defense-in-depth measures. Organizations should immediately apply security updates provided by Microsoft to patch the underlying memory management flaws in Excel versions affected by this vulnerability. It is crucial to maintain up-to-date antivirus signatures that can detect known exploit patterns associated with heap overflows in Office applications. Additionally, implementing application control policies such as AppLocker or Windows Defender Application Control (WDAC) can restrict the execution of untrusted scripts and binaries generated during exploitation attempts. User awareness training remains vital to prevent social engineering attacks that deliver these malicious files via spearphishing campaigns. Enabling Protected View for documents received from uncertain sources adds an extra layer of isolation, ensuring that potentially dangerous content is opened in a sandboxed environment where it cannot interact directly with the host system's memory or file structure until explicitly trusted by the user.