CVE-2026-81396: CWE-121: Stack-based Buffer Overflow in Microsoft Microsoft 365 Apps for Enterprise

This vulnerability (CVE-2026-81396) involves a stack-based buffer overflow in Microsoft Office Excel, part of Microsoft 365 Apps for Enterprise. An attacker could exploit this flaw to execute arbitrary code locally without privileges, requiring user interaction. The CVSS 3.1 vector indicates low attack complexity, no privileges required, but user interaction is needed. The vulnerability impacts confidentiality, integrity, and availability with high impact. Microsoft has published an official security update to address this issue.

Successful exploitation could allow an attacker to execute arbitrary code locally on the affected system, potentially leading to full compromise of the affected application and system. The vulnerability impacts confidentiality, integrity, and availability at a high level. However, exploitation requires local access and user interaction.

Microsoft has released an official fix for this vulnerability. Users and administrators should apply the security updates provided by Microsoft as detailed in the vendor advisory at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-81396. Since this is a cloud service, Microsoft manages remediation for the cloud-hosted components. No additional mitigation steps are required beyond applying the official patch.