Advisoriesby IbisMicrosoftCVE-2026-55899
Microsoft Office Excel: stack buffer overflow
Fix: upgrade to 16.0.5561.1001 or later (3 fixed versions below)
Stack-based buffer overflow in Microsoft Office Excel allows an unauthorized attacker to execute code locally.
Affected versions
| Package | Affected | Fixed in |
|---|---|---|
| Microsoft 365 Apps for Enterprise Product | >= 16.0.1, < https://aka.ms/OfficeSecurityReleases | https://aka.ms/OfficeSecurityReleases |
| Microsoft Excel 2016 Product | >= 16.0.0.0, < 16.0.5561.1001 | 16.0.5561.1001 |
| Microsoft Office 2019 Product | >= 19.0.0, < https://aka.ms/OfficeSecurityReleases | https://aka.ms/OfficeSecurityReleases |
| Microsoft Office 365 for Mac Product | >= 1.0.0, < 16.111.26071215 | 16.111.26071215 |
| Microsoft Office LTSC 2021 Product | >= 16.0.1, < https://aka.ms/OfficeSecurityReleases | https://aka.ms/OfficeSecurityReleases |
| Microsoft Office LTSC 2024 Product | >= 16.0.0, < https://aka.ms/OfficeSecurityReleases | https://aka.ms/OfficeSecurityReleases |
| Microsoft Office LTSC for Mac 2021 Product | >= 16.0.1, < 16.111.26071215 | 16.111.26071215 |
| Microsoft Office LTSC for Mac 2024 Product | >= 16.0.0, < 16.111.26071215 | 16.111.26071215 |
| Office Online Server Product | >= 16.0.0.0, < 16.0.10417.20175 | 16.0.10417.20175 |