PT-2026-40216 · Microsoft · Hyper-V+1

Published 2026-05-12 · Updated 2026-05-13 · CVE-2026-40402

Positive Technologies (AI Summary)

CVSS v3.1

9.3

Critical

Base vector

AV:L/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H

Name of the Vulnerable Software and Affected Versions Windows Hyper-V (affected versions not specified)

Description A use after free issue in Windows Hyper-V allows an unauthorized attacker to perform a guest-to-host attack to elevate privileges locally to SYSTEM level. Use after free is a memory corruption flaw that occurs when an application continues to use a pointer after it has been freed.

Recommendations At the moment, there is no information about a newer version that contains a fix for this vulnerability.

Use After Free

Weakness Enumeration

CWE-416

Related Identifiers

BDU:2026-06858

CVE-2026-40402

Affected Products

Hyper-V

Windows

References · 8

• https://bdu.fstec.ru/vul/2026-06858 · Security Note
• https://msrc.microsoft.com/update-guide/en-US/advisory/CVE-2026-40402 · Vendor Advisory
• https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-40402 · Vendor Advisory
• http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2026-40402 · Security Note
• https://nvd.nist.gov/vuln/detail/CVE-2026-40402 · Security Note
• https://twitter.com/lyrie_ai/status/2054503733783101807 · Twitter Post
• https://twitter.com/windowsforum/status/2054319874378256881 · Twitter Post
• https://reddit.com/r/Automox/comments/1tbczuc/may_2026_patch_tuesday_breakdown_two_preauth_98 · Reddit Post