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CVE-2026-21259— Microsoft Excel Elevation of Privilege Vulnerability

Quick assessment

Affected
Microsoft Microsoft 365 Apps for Enterprise
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Microsoft Excel是美国微软（Microsoft）公司的一款Office套件中的电子表格处理软件。 Microsoft Excel存在安全漏洞。攻击者利用该漏洞可以提升权限。以下产品和版本受到影响：Office Online Server,Microsoft Office 2019 for 32-bit editions,Microsoft Office 2019 for 64-bit editions,Microsoft 365 Apps for Enterprise for 32-bit

CVSS 7.8 · High EPSS 0.56% · P45

Possible ATT&CK Techniques 1 AI

T1203 · Exploitation for Client Execution

Affected Version Matrix 6

VendorProduct Version RangeStatus
Microsoft Microsoft 365 Apps for Enterprise 16.0.1< https://aka.ms/OfficeSecurityReleases affected
Microsoft Microsoft Excel 2016 16.0.0.0< 16.0.5539.1002 affected
Microsoft Microsoft Office 2019 19.0.0< https://aka.ms/OfficeSecurityReleases affected
Microsoft Microsoft Office LTSC 2021 16.0.1< https://aka.ms/OfficeSecurityReleases affected
Microsoft Microsoft Office LTSC 2024 16.0.0< https://aka.ms/OfficeSecurityReleases affected
Microsoft Office Online Server 16.0.0.0< 16.0.10417.20097 affected
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I. Basic Information for CVE-2026-21259

Vulnerability Information
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Vulnerability Title
Microsoft Excel Elevation of Privilege Vulnerability
Source: CVE Program / CVE List V5
Vulnerability Description
Heap-based buffer overflow in Microsoft Office Excel allows an unauthorized attacker to elevate privileges locally.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
堆缓冲区溢出
Source: CVE Program / CVE List V5
Vulnerability Title
Microsoft Excel 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Microsoft Excel是美国微软（Microsoft）公司的一款Office套件中的电子表格处理软件。 Microsoft Excel存在安全漏洞。攻击者利用该漏洞可以提升权限。以下产品和版本受到影响：Office Online Server,Microsoft Office 2019 for 32-bit editions,Microsoft Office 2019 for 64-bit editions,Microsoft 365 Apps for Enterprise for 32-bit
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
Microsoft Microsoft 365 Apps for Enterprise 16.0.1 ~ https://aka.ms/OfficeSecurityReleases -
Microsoft Microsoft Excel 2016 16.0.0.0 ~ 16.0.5539.1002 -
Microsoft Microsoft Office 2019 19.0.0 ~ https://aka.ms/OfficeSecurityReleases -
Microsoft Microsoft Office LTSC 2021 16.0.1 ~ https://aka.ms/OfficeSecurityReleases -
Microsoft Microsoft Office LTSC 2024 16.0.0 ~ https://aka.ms/OfficeSecurityReleases -
Microsoft Office Online Server 16.0.0.0 ~ 16.0.10417.20097 -

II. Public POCs for CVE-2026-21259

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III. Intelligence Information for CVE-2026-21259

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Same Patch Batch · Microsoft · 2026-02-10 · 54 CVEs total

CVE-2026-21531 9.8 CRITICAL Azure SDK for Python Remote Code Execution Vulnerability
CVE-2026-21518 8.8 HIGH GitHub Copilot and Visual Studio Code Security Feature Bypass Vulnerability
CVE-2026-21255 8.8 HIGH Windows Hyper-V Security Feature Bypass Vulnerability
CVE-2026-21256 8.8 HIGH GitHub Copilot and Visual Studio Remote Code Execution Vulnerability
CVE-2026-21513 8.8 HIGH MSHTML Framework Security Feature Bypass Vulnerability
CVE-2026-21510 8.8 HIGH Windows Shell Security Feature Bypass Vulnerability
CVE-2026-21537 8.8 HIGH Microsoft Defender for Endpoint Linux Extension Remote Code Execution Vulnerability
CVE-2026-21516 8.8 HIGH GitHub Copilot for Jetbrains Remote Code Execution Vulnerability
CVE-2026-21228 8.1 HIGH Azure Local Remote Code Execution Vulnerability
CVE-2026-21523 8.0 HIGH GitHub Copilot and Visual Studio Code Remote Code Execution Vulnerability
CVE-2026-21229 8.0 HIGH Power BI Remote Code Execution Vulnerability
CVE-2026-21257 8.0 HIGH GitHub Copilot and Visual Studio Elevation of Privilege Vulnerability
CVE-2026-21239 7.8 HIGH Windows Kernel Elevation of Privilege Vulnerability
CVE-2026-21514 7.8 HIGH Microsoft Word Security Feature Bypass Vulnerability
CVE-2026-21240 7.8 HIGH Windows HTTP.sys Elevation of Privilege Vulnerability
CVE-2026-20841 7.8 HIGH Windows Notepad App Remote Code Execution Vulnerability
CVE-2026-21533 7.8 HIGH Windows Remote Desktop Services Elevation of Privilege Vulnerability
CVE-2026-21236 7.8 HIGH Windows Ancillary Function Driver for WinSock Elevation of Privilege Vulnerability
CVE-2026-21246 7.8 HIGH Windows Graphics Component Elevation of Privilege Vulnerability
CVE-2026-21519 7.8 HIGH Desktop Window Manager Elevation of Privilege Vulnerability

Showing top 20 of 54 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Microsoft 365 Apps for Enterprise
Same vendor: Microsoft
Same weakness: CWE-122

V. Comments for CVE-2026-21259

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