CVE-2026-20838: Windows Kernel Information Disclosure Vulnerability

Severity: medium (CVSS 5.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.7% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-01-13 · updated 2026-07-30
Weakness: CWE-209

Description

Generation of error message containing sensitive information in Windows Kernel allows an authorized attacker to disclose information locally.

Affected products

Microsoft Windows 11: before 10.0.22631.6491 — fixed in 10.0.22631.6491
Microsoft Windows 11: before 10.0.26100.7623 — fixed in 10.0.26100.7623
Microsoft Windows 11 25H2: before 10.0.26200.7623 — fixed in 10.0.26200.7623
Microsoft Windows Server 2022: before 10.0.20348.4648 — fixed in 10.0.20348.4648
Microsoft Windows Server 2022, 23H2 Edition (Server Core installation): before 10.0.25398.2092 — fixed in 10.0.25398.2092
Microsoft Windows Server 2025: before 10.0.26100.32230 — fixed in 10.0.26100.32230
Microsoft Windows 11: from 10.0.22631.0 before 10.0.22631.6491 — fixed in 10.0.22631.6491
Microsoft Windows 11: from 10.0.26100.0 before 10.0.26100.7623 — fixed in 10.0.26100.7623
Microsoft Windows 11 25H2: from 10.0.26200.0 before 10.0.26200.7623 — fixed in 10.0.26200.7623
Microsoft Windows Server 2022: from 10.0.20348.0 before 10.0.20348.4648 — fixed in 10.0.20348.4648
Microsoft Windows Server 2022, 23H2 Edition (Server Core installation): from 10.0.25398.0 before 10.0.25398.2092 — fixed in 10.0.25398.2092
Microsoft Windows Server 2025: from 10.0.26100.0 before 10.0.26100.32230 — fixed in 10.0.26100.32230

How to fix

Upgrade to a fixed version: Microsoft Windows 11 10.0.22631.6491; Microsoft Windows 11 10.0.26100.7623; Microsoft Windows 11 25H2 10.0.26200.7623; Microsoft Windows Server 2022 10.0.20348.4648; Microsoft Windows Server 2022, 23H2 Edition (Server Core installation) 10.0.25398.2092; Microsoft Windows Server 2025 10.0.26100.32230; Microsoft Windows 11 10.0.22631.6491; Microsoft Windows 11 10.0.26100.7623; Microsoft Windows 11 25H2 10.0.26200.7623; Microsoft Windows Server 2022 10.0.20348.4648; Microsoft Windows Server 2022, 23H2 Edition (Server Core installation) 10.0.25398.2092; Microsoft Windows Server 2025 10.0.26100.32230. Check the vendor advisory for mitigations.

References

https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-20838

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