CVE-2026-55122 Details

A vulnerability allowing out-of-bounds read has been identified in Microsoft Office Excel. This issue enables an unauthorized attacker to locally disclose information by exploiting the vulnerability, which involves reading small portions of heap memory. The vulnerability affects multiple versions of Microsoft Excel, including Excel 2016 (both 32-bit and 64-bit editions), Office LTSC for Mac 2021 and 2024, Office LTSC 2021 and 2024 for Windows (both 32-bit and 64-bit editions), Office 2019 (also in 32-bit and 64-bit editions), and Microsoft 365 Apps for Enterprise (again, both 32-bit and 64-bit).

Users can download the security update for this vulnerability through the Microsoft Update Catalog. For Office LTSC for Mac 2021 and 2024, the security update is also available via the Mac App Store.