This vulnerability (CVE-2026-45456) is a type confusion flaw (CWE-843) in Microsoft 365 Apps for Enterprise that permits an unauthorized attacker to execute code locally by accessing resources using incompatible types. The CVSS 3.1 base score is 8.4, reflecting high impact on confidentiality, integrity, and availability with low attack complexity and no required privileges or user interaction. Microsoft has published an official fix and manages remediation for this cloud service. The affected version explicitly identified is 16.0.1.

Successful exploitation allows an attacker to execute arbitrary code locally, potentially leading to full compromise of the affected system's confidentiality, integrity, and availability. The vulnerability requires local access but no privileges or user interaction, making it a significant risk if an attacker can gain local access.

An official fix is available from Microsoft. Since this is a cloud-hosted service, Microsoft manages remediation server-side. Users and administrators should ensure their Microsoft 365 Apps for Enterprise installations are updated to the fixed version as per the vendor advisory at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-45456.