CVE-2026-21259

HIGH

Microsoft Office Excel - Privilege Escalation

Title source: llm
STIX 2.1

Description

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

References (1)

Scores

CVSS v3 7.8
EPSS 0.0003
EPSS Percentile 8.9%
Attack Vector LOCAL
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

CISA SSVC

Vulnrichment
Exploitation none
Automatable no
Technical Impact total

Details

CWE
CWE-122 CWE-787
Status published
Products (12)
microsoft/365_apps (2 CPE variants)
microsoft/excel 2016 (2 CPE variants)
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 2019 (2 CPE variants)
Microsoft/Office Online Server 16.0.0.0 - 16.0.10417.20097
microsoft/office_long_term_servicing_channel 2021 (2 CPE variants)
... and 2 more
Published Feb 10, 2026
Tracked Since Feb 18, 2026