CVE-2026-21259

HIGH
2026-02-10 [email protected]
7.8
CVSS 3.1
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CVSS Vector

CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Attack Vector
Local
Attack Complexity
Low
Privileges Required
None
User Interaction
Required
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

Lifecycle Timeline

2
Analysis Generated
Mar 12, 2026 - 22:02 vuln.today
CVE Published
Feb 10, 2026 - 18:16 nvd
HIGH 7.8

Tags

Microsoft Buffer Overflow Heap Overflow Office Long Term Servicing Channel 365 Apps Excel Office Online Server Office

Description

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

Analysis

Privilege escalation in Microsoft Office Excel (including 365 Apps and Long Term Servicing Channel) via heap-based buffer overflow allows local attackers with user interaction to gain elevated system privileges. The vulnerability affects multiple Office product lines and currently lacks a security patch. …

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Remediation

Within 24 hours: Inventory all systems running affected Microsoft Office Excel versions and assess user access patterns. Within 7 days: Implement network segmentation to restrict lateral movement from compromised endpoints; disable Excel macros via Group Policy where operationally feasible; restrict local administrator privileges. …

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Priority Score

39
Low Medium High Critical
KEV: 0
EPSS: +0.0
CVSS: +39
POC: 0

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CVE-2026-21259 vulnerability details – vuln.today
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