CVE-2026-21259: Microsoft Excel Elevation of Privilege Vulnerability
Heap-based buffer overflow in Microsoft Office Excel allows an unauthorized attacker to elevate privileges locally.
Other sources
Microsoft Excel Elevation of Privilege Vulnerability
— Microsoft
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade to a fixed release to a version that resolves this vulnerability.
Fixed in 16.0.5539.1002Patch KB5002837 - Upgrade
Upgrade to a fixed release to a version that resolves this vulnerability.
Fixed in https://aka.ms/OfficeSecurityReleases - Upgrade
Upgrade to a fixed release to a version that resolves this vulnerability.
Fixed in 16.0.10417.20097Patch KB5002835
Event History
Frequently Asked Questions
What is the severity of CVE-2026-21259?
CVE-2026-21259 has been rated as a high severity vulnerability due to its potential to allow elevation of privileges.
How do I fix CVE-2026-21259?
To address CVE-2026-21259, apply the latest patches provided by Microsoft for affected versions of Excel.
Which versions of Microsoft Excel are affected by CVE-2026-21259?
CVE-2026-21259 affects Microsoft Excel 2016, Office LTSC 2021, Office LTSC 2024, and Office 2019 among others.
What type of vulnerability is CVE-2026-21259?
CVE-2026-21259 is a heap-based buffer overflow vulnerability that can lead to local privilege escalation.
Can CVE-2026-21259 be exploited remotely?
No, CVE-2026-21259 requires local access to the system to exploit the vulnerability.