CVE-2026-21259HighCVSS 7.8
Microsoft Excel Elevation of Privilege Vulnerability
🔗 CVE IDs covered (1)
📋 Description
Heap-based buffer overflow in Microsoft Office Excel allows an unauthorized attacker to elevate privileges locally.
🎯 Affected products11
- Microsoft 365 Apps for Enterprise for 32-bit Systems
- Microsoft 365 Apps for Enterprise for 64-bit Systems
- Microsoft Excel 2016 (32-bit edition)
- Microsoft Excel 2016 (64-bit edition)
- Microsoft Office 2019 for 32-bit editions
- Microsoft Office 2019 for 64-bit editions
- Microsoft Office LTSC 2021 for 32-bit editions
- Microsoft Office LTSC 2021 for 64-bit editions
- Microsoft Office LTSC 2024 for 32-bit editions
- Microsoft Office LTSC 2024 for 64-bit editions
- Office Online Server
✅ Remediation
KB5002835 (Security Update) — fixed build 16.0.10417.20097 KBClick to Run (Security Update) — fixed build https://aka.ms/OfficeSecurityReleases KB5002837 (Security Update) — fixed build 16.0.5539.1002
🔗 References (6)
- advisoryhttps://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-21259
- patchhttps://www.microsoft.com/en-us/download/details.aspx?id=108551
- referencehttps://support.microsoft.com/help/5002835
- referencehttps://docs.microsoft.com/en-us/officeupdates/microsoft365-apps-security-updates
- patchhttps://www.microsoft.com/en-us/download/details.aspx?id=108555
- referencehttps://support.microsoft.com/help/5002837