CVE-2026-69686: CWE-121: Stack-based Buffer Overflow in Microsoft Microsoft 365 Apps for Enterprise

This vulnerability, identified as CVE-2026-69686 and classified under CWE-121 (stack-based buffer overflow), exists in Microsoft Office Word within Microsoft 365 Apps for Enterprise. It enables remote code execution by an unauthorized attacker over a network. The CVSS v3.1 base score is 8.8, indicating high severity, with attack vector network, low attack complexity, no privileges required, user interaction required, and impacts to confidentiality, integrity, and availability. Multiple version ranges are affected, all prior to specific fixed versions. Microsoft has issued an official fix and manages remediation for this cloud service. The vendor advisory is available at the Microsoft Security Response Center.

Successful exploitation of this vulnerability could allow an attacker to execute arbitrary code remotely on the affected system, potentially leading to full compromise of confidentiality, integrity, and availability of the affected Microsoft 365 Apps for Enterprise installation. This could enable actions such as data theft, system manipulation, or denial of service.

An official fix is available from Microsoft. Since this is a cloud-hosted service, Microsoft manages remediation server-side. Users and administrators should apply the official updates as provided in the Microsoft advisory at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-69686 to mitigate this vulnerability.