CVE-2026-33826: Windows Active Directory Remote Code Execution Vulnerability

Severity: high (CVSS 8.0 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.5% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-04-14 · updated 2026-10-15
Weakness: CWE-20

Description

Improper input validation in Windows Active Directory allows an authorized attacker to execute code over an adjacent network.

Affected products

Microsoft Windows Server 2012: r2
Microsoft Windows Server 2016: before 10.0.14393.9060 — fixed in 10.0.14393.9060
Microsoft Windows Server 2019: before 10.0.17763.8644 — fixed in 10.0.17763.8644
Microsoft Windows Server 2022: before 10.0.20348.5020 — fixed in 10.0.20348.5020
Microsoft Windows Server 2022, 23H2 Edition (Server Core installation): before 10.0.25398.2274 — fixed in 10.0.25398.2274
Microsoft Windows Server 2025: before 10.0.26100.32690 — fixed in 10.0.26100.32690
Microsoft Windows Server 2012 R2: from 6.3.9600.0 before 6.3.9600.23132 — fixed in 6.3.9600.23132
Microsoft Windows Server 2016: from 10.0.14393.0 before 10.0.14393.9060 — fixed in 10.0.14393.9060
Microsoft Windows Server 2019: from 10.0.17763.0 before 10.0.17763.8644 — fixed in 10.0.17763.8644
Microsoft Windows Server 2022: from 10.0.20348.0 before 10.0.20348.5020 — fixed in 10.0.20348.5020
Microsoft Windows Server 2022, 23H2 Edition (Server Core installation): from 10.0.25398.0 before 10.0.25398.2274 — fixed in 10.0.25398.2274
Microsoft Windows Server 2025: from 10.0.26100.0 before 10.0.26100.32690 — fixed in 10.0.26100.32690

How to fix

Upgrade to a fixed version: Microsoft Windows Server 2016 10.0.14393.9060; Microsoft Windows Server 2019 10.0.17763.8644; Microsoft Windows Server 2022 10.0.20348.5020; Microsoft Windows Server 2022, 23H2 Edition (Server Core installation) 10.0.25398.2274; Microsoft Windows Server 2025 10.0.26100.32690; Microsoft Windows Server 2012 R2 6.3.9600.23132; Microsoft Windows Server 2016 10.0.14393.9060; Microsoft Windows Server 2019 10.0.17763.8644; Microsoft Windows Server 2022 10.0.20348.5020; Microsoft Windows Server 2022, 23H2 Edition (Server Core installation) 10.0.25398.2274; Microsoft Windows Server 2025 10.0.26100.32690. Check the vendor advisory for mitigations.

References

https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-33826

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