Threat Intelligence / CVE / CVE-2026-40402

CVE-2026-40402 — Microsoft Windows 11 version 23H2

CVSS v3.1 9.3 (CRITICAL) · EPSS 0.0% (higher than 18.1% of all scored CVEs) · Priority 5.4/10 · Published 2026-05-12

As of 2026-05-26, CVE-2026-40402 is a CRITICAL-severity vulnerability in Microsoft Windows 11 version 23H2, CVSS v3.1 9.3, EPSS 0.0% (18.1th percentile). Threadlinqs Intelligence links 1 tracked threat campaign to CVE-2026-40402, most recently “Microsoft May 2026 Patch Tuesday — 137 CVEs, 31 Critical (16 RCE) Including CVE-2026-41089 Pre-Auth Netlogon Stack Overflow on Domain Controllers”.

Last updated: 2026-05-26

What is CVE-2026-40402?

Use after free in Windows Hyper-V allows an unauthorized attacker to elevate privileges locally.

The record classifies CVE-2026-40402 under weakness class CWE-416. Its CVSS v3 base vector states that the flaw requires local access to the host, needs no prior authentication, needs no user interaction, and has high impact on confidentiality, integrity, availability. 3 affected-product entries are recorded, across 1 vendor, listed below. The identifier was first published 123 days ago.

Severity and exploitation probability

CVSS v3.1 base score
9.3 — CRITICAL
CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H/E:U/RL:O/RC:C
EPSS (FIRST)
0.0% probability of exploitation in the next 30 days, higher than 18.1% of all scored CVEs
CISA KEV
Not listed in the CISA Known Exploited Vulnerabilities catalog
Threadlinqs priority
5.4/10 — a Threadlinqs composite of the CVSS base score, the EPSS percentile and public exploit availability
Published
2026-05-12, last modified 2026-05-26

Is CVE-2026-40402 being exploited?

It currently carries a trending score of 10 in the Threadlinqs vulnerability feed.

Affected products and versions

How to fix CVE-2026-40402

No vendor patch reference has been recorded for CVE-2026-40402 in the tracked sources. Follow the references below for a fix, and treat the products listed above as exposed until the vendor states otherwise.

Threat activity tracking CVE-2026-40402

1 tracked threat in the Threadlinqs corpus references CVE-2026-40402, either in the campaign’s CVE list or as an indicator on the campaign record.

Sources

Seeded from cveorg and not yet processed by the Threadlinqs enrichment pipeline, so blank CVSS, EPSS or KEV fields above mean NOT MEASURED rather than measured-absent.

Full detection coverage & IOCs for threats exploiting CVE-2026-40402 are available via the Threadlinqs MCP server (Purple tier). View plans →

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