CVE-2026-40402CriticalMicrosoft CVSS 9.3CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H/E:U/RL:O/RC:C

Microsoft security update for CVE-2026-40402 — Windows

Published
May 22, 2026
Last Modified
—

🔗 CVE IDs covered (1)

CVE-2026-40402 →

📋 Microsoft's advisory

EchelonGraph does not copy Microsoft's advisory page: its FAQ and remediation text are not shown here. Read the advisory on https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-40402. This page also shows what EchelonGraph holds for CVE-2026-40402, with the description from its CVE record, which the CVE Numbering Authority that assigned the CVE wrote: for a CVE Microsoft assigned, often in the words of Microsoft's own advisory.

🎯 Affected products4

  • Windows 11 Version 23H2 for ARM64-based Systems
  • Windows 11 Version 23H2 for x64-based Systems
  • Windows Server 2022
  • Windows Server 2022 (Server Core installation)

✅ Updates Microsoft lists: 4 KB articles

4 rows: one per KB article or update, update type and fixed build. Their details are on Microsoft's advisory.

KB articleUpdateFixed build
KB5087545Security Update10.0.20348.5139
KB5087424Security Hotpatch Update10.0.20348.5074
KB5087420Security Update10.0.22631.7079
KB5093998Security Update10.0.22631.7219

🧭 EchelonGraph on CVE-2026-40402

EchelonGraph score
9.3 CRITICAL
CISA KEV
Not listed
Fix status
A fix is available — apply it.

Description from the CVE record (CVE.org), as published by its numbering authority

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

Published by Microsoft Corporation, the CVE Numbering Authority that assigned CVE-2026-40402, in its CVE record at CVE.org; reused under the CVE Program's Terms of Use (its licence and MITRE's copyright notice are in our Terms of Service).

🔗 References (9)