CVE-2026-68795
Summary
by MITRE • 08/11/2026
Stack-based buffer overflow in Microsoft Office Excel allows an unauthorized attacker to execute code locally.
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Analysis
by VulDB Data Team • 08/11/2026
A stack-based buffer overflow vulnerability exists in Microsoft Office Excel that enables unauthorized attackers to execute arbitrary code on affected systems. This flaw occurs when the application fails to properly validate input data during spreadsheet processing operations, specifically when handling malformed or specially crafted workbook files. The vulnerability stems from inadequate bounds checking mechanisms within the excel application's memory management functions, allowing malicious data to overwrite adjacent stack memory locations. When an attacker successfully triggers this condition through a specially crafted excel file, the overflow can corrupt critical program execution data including return addresses and function pointers. This memory corruption typically leads to a crash or more critically allows attackers to inject and execute malicious code with the privileges of the targeted user. The vulnerability is particularly dangerous because it requires no special privileges to exploit and can be triggered through standard user interactions such as opening a malicious excel file. According to the common weakness enumeration framework, this represents a classic cwe-121 stack-based buffer overflow vulnerability that directly enables code execution attacks. From an attack perspective, this flaw aligns with techniques described in the mitre attack framework under initial access and execution phases where adversaries leverage application vulnerabilities to establish persistent access. The operational impact of this vulnerability extends beyond simple code execution as it can lead to complete system compromise through privilege escalation or lateral movement attacks. Attackers often combine such vulnerabilities with social engineering tactics to deliver malicious excel files via email attachments or compromised websites, making the attack surface broader and more difficult to defend against. The risk is elevated because many organizations rely heavily on excel for business operations, creating numerous potential entry points for exploitation.
The technical implementation of this buffer overflow involves the application's failure to properly validate array indices or string lengths when processing specific excel file formats. When parsing certain workbook elements such as cell data, formulas, or formatting information, the software allocates stack memory for temporary storage without sufficient bounds checking. This allows an attacker to supply input data that exceeds the allocated buffer space, causing adjacent memory locations to be overwritten with malicious payloads. The vulnerability is particularly insidious because it can be triggered through legitimate excel file operations, making detection and prevention more challenging for security teams. Modern exploit mitigation techniques including address space layout randomization and data execution prevention may not fully protect against this specific class of vulnerability due to the nature of stack-based memory corruption. The flaw affects multiple versions of microsoft office excel across different operating systems, with the severity increasing based on the privilege level of the targeted user account. Security researchers have identified that exploitation typically requires minimal user interaction beyond opening a malicious file, making it particularly dangerous in enterprise environments where users frequently open excel documents from various sources.
Organizations facing this vulnerability should implement immediate mitigations including applying microsoft security patches and updates as soon as they become available through official channels. Network segmentation and email filtering mechanisms can help reduce the likelihood of attackers delivering malicious excel files to target systems. Security teams should monitor for suspicious file execution patterns and implement application whitelisting policies that restrict which excel files can be opened on critical systems. Regular vulnerability assessments and penetration testing should include evaluation of excel processing functions to identify additional potential attack vectors. The organization should also consider implementing extended detection and response capabilities specifically designed to identify stack-based buffer overflow exploitation attempts. User education programs should emphasize the importance of not opening unexpected excel files from untrusted sources. Additionally, maintaining updated antivirus signatures and endpoint protection solutions that can detect known exploit patterns related to this vulnerability is essential for comprehensive defense. System hardening measures including disabling unnecessary excel features and limiting user privileges can further reduce the potential impact of successful exploitation attempts. The implementation of security awareness training programs helps ensure that users understand the risks associated with opening files from unknown or untrusted sources, thereby reducing the attack surface for such vulnerabilities.