This vulnerability (CVE-2026-63518) is a heap-based buffer overflow in Microsoft Office Word, part of Microsoft 365 Apps for Enterprise. It enables an unauthorized attacker to execute arbitrary code locally. The CVSS 3.1 base score is 7.8, reflecting high impact on confidentiality, integrity, and availability, with low attack complexity but requiring user interaction. Microsoft has issued an official fix and manages remediation for this cloud service. No known exploits are currently reported in the wild.

Successful exploitation could allow an attacker to execute arbitrary code on the local system, potentially leading to full compromise of the affected application and access to sensitive data. The vulnerability affects confidentiality, integrity, and availability with high impact. However, exploitation requires local access and user interaction.

An official fix is available from Microsoft. Since this is a cloud-hosted service, Microsoft manages remediation server-side. Users and administrators should ensure that Microsoft 365 Apps for Enterprise are updated to the fixed version as per the vendor advisory at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-63518.