CVE-2026-40407: Windows Common Log File System Driver Elevation of Privilege Vulnerability

Severity: high (CVSS 7.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.3% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-05-12 · updated 2026-06-17
Weakness: CWE-122

Description

Heap-based buffer overflow in Windows Common Log File System Driver allows an authorized attacker to elevate privileges locally.

Affected products

Microsoft Windows 10 1607: before 10.0.14393.9140 — fixed in 10.0.14393.9140
Microsoft Windows 10: before 10.0.17763.8755 — fixed in 10.0.17763.8755
Microsoft Windows 10: before 10.0.19044.7291 — fixed in 10.0.19044.7291
Microsoft Windows 10: before 10.0.19045.7291 — fixed in 10.0.19045.7291
Microsoft Windows 11: before 10.0.22631.7079 — fixed in 10.0.22631.7079
Microsoft Windows 11: before 10.0.26100.8390 — fixed in 10.0.26100.8390
Microsoft Windows 11 25H2: before 10.0.26200.8390 — fixed in 10.0.26200.8390
Microsoft Windows 11 version 26H1: before 10.0.28000.2113 — fixed in 10.0.28000.2113
Microsoft Windows Server 2012: r2
Microsoft Windows Server 2016: before 10.0.14393.9140 — fixed in 10.0.14393.9140
Microsoft Windows Server 2019: before 10.0.17763.8755 — fixed in 10.0.17763.8755
Microsoft Windows Server 2022: before 10.0.20348.5074 — fixed in 10.0.20348.5074
Microsoft Windows Server 2022, 23H2 Edition (Server Core installation): before 10.0.25398.2330 — fixed in 10.0.25398.2330
Microsoft Windows Server 2025: before 10.0.26100.32772 — fixed in 10.0.26100.32772

How to fix

Upgrade to a fixed version: Microsoft Windows 10 1607 10.0.14393.9140; Microsoft Windows 10 10.0.17763.8755; Microsoft Windows 10 10.0.19044.7291; Microsoft Windows 10 10.0.19045.7291; Microsoft Windows 11 10.0.22631.7079; Microsoft Windows 11 10.0.26100.8390; Microsoft Windows 11 25H2 10.0.26200.8390; Microsoft Windows 11 version 26H1 10.0.28000.2113; Microsoft Windows Server 2016 10.0.14393.9140; Microsoft Windows Server 2019 10.0.17763.8755; Microsoft Windows Server 2022 10.0.20348.5074; Microsoft Windows Server 2022, 23H2 Edition (Server Core installation) 10.0.25398.2330. Check the vendor advisory for mitigations.

References

https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-40407

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