CVE-2026-55053 Details

A heap-based buffer overflow vulnerability has been identified in Microsoft Office Excel. This issue allows an unauthorized attacker to execute code locally. The vulnerability affects multiple versions of Microsoft Office, including Office 2019 (32-bit and 64-bit editions), Office 365 for Mac, Office LTSC for Mac 2024, Office LTSC 2021 (32-bit and 64-bit editions), Office LTSC for Mac 2021, and Microsoft 365 Apps for Enterprise (both 32-bit and 64-bit systems).

Users can download the security update for their specific version of Microsoft Office. For Office 2019 and Office LTSC 2021, security updates are available through the Microsoft Update Catalog. Office 365 Apps for Enterprise users can download the security update from the Microsoft 365 Admin Center. For Office Online Server, the security update can be downloaded from the Microsoft Download Center.