CVE-2026-21259

CWE-122 — Heap-based Buffer OverflowCWE-787 — Out-of-bounds Write5 documents5 sources
Severity
7.8HIGH
EPSS
0.0%
top 92.41%
CISA KEV
Not in KEV
Exploit
No known exploits
Affected products
9
Microsoft Microsoft 365 Apps FOR EnterpriseMicrosoft Microsoft Excel 2016Microsoft Microsoft Office 2019+6 more
Timeline
PublishedFeb 10

Description

Heap-based buffer overflow in Microsoft Office Excel allows an unauthorized attacker to elevate privileges locally.

CVSS vector

CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:HExploitability: 1.8 | Impact: 5.9

Affected Packages10 packages

▶CVEListV5microsoft/microsoft_excel_201616.0.0.0 — 16.0.5539.1002
▶CVEListV5microsoft/office_online_server16.0.0.0 — 16.0.10417.20097
▶NVDmicrosoft/office_online_server< 16.0.10417.20097
▶CVEListV5microsoft/microsoft_office_201919.0.0 — https://aka.ms/OfficeSecurityReleases
▶CVEListV5microsoft/microsoft_office_ltsc_202116.0.1 — https://aka.ms/OfficeSecurityReleases

🔴Vulnerability Details

2
CVEList
Microsoft Excel Elevation of Privilege Vulnerability↗2026-02-10
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GHSA
GHSA-pw6x-8hxj-hv8c: Heap-based buffer overflow in Microsoft Office Excel allows an unauthorized attacker to elevate privileges locally↗2026-02-10
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📋Vendor Advisories

1
Microsoft
Microsoft Excel Elevation of Privilege Vulnerability↗2026-02-10
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🕵️Threat Intelligence

1
Wiz
CVE-2026-21259 Impact, Exploitability, and Mitigation Steps | Wiz↗
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