This vulnerability (CVE-2026-55949) in Microsoft 365 Apps for Enterprise arises from the use of an uninitialized resource in Microsoft Office Excel. The flaw could enable an unauthorized attacker to execute code locally on the affected system. The CVSS 3.1 base score is 7.8, indicating high severity with local attack vector, low attack complexity, no privileges required, user interaction required, and high impact on confidentiality, integrity, and availability. 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 unauthorized attacker to execute code locally on the affected system, potentially leading to full compromise of confidentiality, integrity, and availability of the affected Microsoft 365 Apps for Enterprise instance. The vulnerability is rated high severity with a CVSS score of 7.8. No known exploits have been reported in the wild.

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 environment is updated according to the vendor advisory at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-55949. No additional action is required beyond applying the official fix.