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CVE-2026-40402

Microsoft Windows 11 23h2 use-after-free

9.3 CRITICALEPSS 0.36%
  1. Published12 May 2026

Description

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

CVSS 3.1 breakdown

Attack vectorLocal
Attack complexityLow
Privileges requiredNone
User interactionNone
ScopeChanged
ConfidentialityHigh
IntegrityHigh
AvailabilityHigh
CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H

Affected products

Microsoft Windows 11 23h2< 10.0.22631.7079
Microsoft Windows Server 2022< 10.0.20348.5074

Remediation

Fixed in
Microsoft Windows 11 23h2≥ 10.0.22631.7079
Microsoft Windows Server 2022≥ 10.0.20348.5074

References

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Frequently asked

Is CVE-2026-40402 being actively exploited?

CVE-2026-40402 is not in the CISA KEV catalog. Its EPSS exploit probability is 0.36%.

How severe is CVE-2026-40402?

CVE-2026-40402 has a CVSS 3.1 base score of 9.3, rated critical. EPSS estimates a 0.36% probability of exploitation.

Which products are affected by CVE-2026-40402?

Affected products include Microsoft Windows 11 23h2, Microsoft Windows Server 2022.

How do I fix CVE-2026-40402?

Upgrade affected software to a fixed version, for example Microsoft Windows 11 23h2 10.0.22631.7079, Microsoft Windows Server 2022 10.0.20348.5074 or later, then confirm no affected versions remain in your inventory.

How Secuno handles this

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Data from the NVD, CISA KEV catalog and FIRST EPSS. CVSS 3.1 base score shown where available.