CVE-2026-40420

Severity CVSS v4.0:

Pending analysis

Type:

CWE-284 Improper Access Control

Publication date:

12/05/2026

Last modified:

12/05/2026

Description

Improper access control in Microsoft Office Click-To-Run allows an authorized attacker to elevate privileges locally.

Impact

Vector 3.x

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H CVSS v3.1 Severity and Metrics:

Base Score: 8.80 HIGH
Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H

Attack Vector (AV): Local
Attack Complexity (AC): Low
Privileges Required (PR): Low
User Interaction (UI): None
Scope (S): Changed
Confidentiality (C): High
Integrity (I): High
Availability (A): High

Base Score 3.x

8.80

Severity 3.x

HIGH

References to Advisories, Solutions, and Tools

https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-40420