CVE intelligence

CVE-2026-40366

Vulnerability intelligence

Published May 12, 2026Sources checked Nov 11, 2026

8.4HIGHCVSS out of 10

What this means

Review the available evidence

CVE-2026-40366 and is rated High severity with a CVSS score of 8.4. It is not in the current CISA KEV record we collected. That does not prove exploitation has not occurred.

What to do next

Remediation and response

Microsoft Security Response Center guidance

Vendor revision: May 12, 2026

Click to Run Release Notes Install KB5002858.

Vendor-listed releases

https://aka.ms/OfficeSecurityReleases
16.109.26051019
16.0.5552.1000

CISA KEVNot listedBased on the latest collected catalog

EPSS0.4%Estimated 30-day exploitation probability

Ransomware useNot markedCISA KEV ransomware field

Threat actors0Source-linked actor relationships

Overview

What is CVE-2026-40366?

Access of resource using incompatible type ('type confusion') in Microsoft Office Word allows an unauthorized attacker to execute code locally.

Source: NVD