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HIGH · 7.8

CVE-2026-40397

Integer underflow (wrap or wraparound) in Windows Common Log File System Driver allows an authorized attacker to elevate privileges locally.

Vulnerability Description

Integer underflow (wrap or wraparound) in Windows Common Log File System Driver 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< 10.0.14393.9140
MicrosoftWindows 10 1809< 10.0.17763.8755
MicrosoftWindows 10 21H2< 10.0.19044.7291
MicrosoftWindows 10 22H2< 10.0.19045.7291
MicrosoftWindows 11 23H2< 10.0.22631.7079
MicrosoftWindows 11 24H2< 10.0.26100.8390
MicrosoftWindows 11 25H2< 10.0.26200.8390
MicrosoftWindows 11 26H1< 10.0.28000.2113
MicrosoftWindows Server 2012-
MicrosoftWindows Server 2016< 10.0.14393.9140
MicrosoftWindows Server 2019< 10.0.17763.8755
MicrosoftWindows Server 2022< 10.0.20348.5074
MicrosoftWindows Server 2022 23H2< 10.0.25398.2330
MicrosoftWindows Server 2025< 10.0.26100.32772

Related Weaknesses (CWE)

CWE-191

References

FAQ

What is CVE-2026-40397?

CVE-2026-40397 is a vulnerability with a CVSS score of 7.8 (HIGH). Integer underflow (wrap or wraparound) in Windows Common Log File System Driver allows an authorized attacker to elevate privileges locally.

How severe is CVE-2026-40397?

CVE-2026-40397 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-2026-40397?

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.