Is CVE-2026-40420 actively exploited?

No active exploitation of CVE-2026-40420 has been confirmed so far. Continue monitoring, as exploit status can change.

Can CVE-2026-40420 be exploited remotely?

No. CVE-2026-40420 requires local access to exploit.

What is the CVSS score of CVE-2026-40420?

CVE-2026-40420 has a CVSS score of 8.8 (HIGH).

HOME VULNERABILITIESCVE-2026-40420

HIGH

CVE-2026-40420

CWE-284Published: May 12, 2026· Updated: May 13, 2026

8.8

CVSS v3.1

EPSS:0.04%probability of exploitation in 30 daysPercentile:12.3th

Official Description

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

NVD Source

Technical Analysis

CVE-2026-40420 requires local access, meaning attackers must already have a foothold on the target system.

Exploitation requires low privileges, which limits the exposure to scenarios where an attacker has already gained initial access.

A successful exploit results in complete confidentiality breach (data exposure), full integrity compromise (data manipulation), availability disruption (denial of service), with a CVSS base score of 8.8.

The vulnerability has a "Changed" scope, meaning successful exploitation can impact components beyond the vulnerable component itself — such as the host operating system or adjacent services.