CVE-2026-45469 is an integer underflow (wrap or wraparound) vulnerability in Microsoft Office Excel, part of Microsoft 365 Apps for Enterprise. This vulnerability enables an unauthorized attacker to execute code locally. It has a CVSS 3.1 base score of 7.8, indicating high severity. The vulnerability affects version 16.0.1. Microsoft has issued an official fix and manages remediation for this cloud-hosted service. No known exploits have been reported in the wild.

Successful exploitation of this vulnerability could allow an unauthorized attacker to execute arbitrary code locally, potentially leading to full compromise of the affected system. The vulnerability impacts confidentiality, integrity, and availability, all rated high in the CVSS vector.

An official fix is available from Microsoft. Since this is a cloud-hosted service, Microsoft manages the remediation server-side. Users and administrators should follow guidance in the Microsoft advisory at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-45469 to ensure their environment is updated and protected.