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HIGH · 7.8

CVE-2026-20809

Time-of-check time-of-use (toctou) race condition in Windows Kernel Memory allows an authorized attacker to elevate privileges locally.

Vulnerability Description

Time-of-check time-of-use (toctou) race condition in Windows Kernel Memory allows an authorized attacker to elevate privileges locally.

CVSS Score

7.8

HIGH

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Attack Vector
LOCAL
Attack Complexity
LOW
Privileges Required
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
HIGH
Integrity
HIGH
Availability
HIGH

Affected Products

VendorProductVersions
MicrosoftWindows 10 1607< 10.0.14393.8783
MicrosoftWindows 10 1809< 10.0.17763.8276
MicrosoftWindows 10 21H2< 10.0.19044.6809
MicrosoftWindows 10 22H2< 10.0.19045.6809
MicrosoftWindows 11 23H2< 10.0.22631.6491
MicrosoftWindows 11 24H2< 10.0.26100.7623
MicrosoftWindows 11 25H2< 10.0.26200.7623
MicrosoftWindows Server 2012r2
MicrosoftWindows Server 2016< 10.0.14393.8783
MicrosoftWindows Server 2019< 10.0.17763.8276
MicrosoftWindows Server 2022< 10.0.20348.4648
MicrosoftWindows Server 2022 23H2< 10.0.25398.2092
MicrosoftWindows Server 2025< 10.0.26100.32230

Related Weaknesses (CWE)

CWE-122CWE-367

References

FAQ

What is CVE-2026-20809?

CVE-2026-20809 is a vulnerability with a CVSS score of 7.8 (HIGH). Time-of-check time-of-use (toctou) race condition in Windows Kernel Memory allows an authorized attacker to elevate privileges locally.

How severe is CVE-2026-20809?

CVE-2026-20809 has been rated HIGH with a CVSS base score of 7.8/10. Review the CVSS metrics above for detailed severity breakdown.

Is there a patch for CVE-2026-20809?

Check the references section above for vendor advisories and patch information. Affected products include: Microsoft Windows 10 1607, Microsoft Windows 10 1809, Microsoft Windows 10 21H2, Microsoft Windows 10 22H2, Microsoft Windows 11 23H2.