CVE-2026-55131 Details

A heap-based buffer overflow vulnerability has been identified in Microsoft Office Excel. This vulnerability allows an unauthorized attacker to execute code locally. It affects several different versions and editions of Microsoft Excel, including Excel 2016, Excel 2019, Office LTSC 2021, Office LTSC 2024, and Office 365 for Mac. The vulnerability arises from a buffer overflow in the handling of certain data, which can be exploited by crafting a malicious Office file that, when opened by the user, triggers the overflow and allows for arbitrary code execution.

Users can download the security update for this vulnerability through the Microsoft Update Catalog. For Office LTSC 2024, security updates are also available via the Microsoft 365 Apps security update channel.