CVE-2026-20833: Windows Kerberos Information Disclosure Vulnerability

Severity: medium (CVSS 5.5 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: 2026-01-13 · updated 2026-07-30
Weakness: CWE-327

Description

Use of a broken or risky cryptographic algorithm in Windows Kerberos allows an authorized attacker to disclose information locally.

Affected products

Microsoft Windows Server 2008: r2-sp1
Microsoft Windows Server 2012: r2
Microsoft Windows Server 2016: before 10.0.14393.8783 — fixed in 10.0.14393.8783
Microsoft Windows Server 2019: before 10.0.17763.8276 — fixed in 10.0.17763.8276
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 Server 2008 R2 Service Pack 1: from 6.1.7601.0 before 6.1.7601.28117 — fixed in 6.1.7601.28117
Microsoft Windows Server 2008 Service Pack 2: from 6.0.6003.0 before 6.0.6003.23717 — fixed in 6.0.6003.23717
Microsoft Windows Server 2012: from 6.2.9200.0 before 6.2.9200.25868 — fixed in 6.2.9200.25868
Microsoft Windows Server 2012 R2: from 6.3.9600.0 before 6.3.9600.22968 — fixed in 6.3.9600.22968
Microsoft Windows Server 2016: from 10.0.14393.0 before 10.0.14393.8783 — fixed in 10.0.14393.8783
Microsoft Windows Server 2019: from 10.0.17763.0 before 10.0.17763.8276 — fixed in 10.0.17763.8276
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 Server 2016 10.0.14393.8783; Microsoft Windows Server 2019 10.0.17763.8276; 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 Server 2008 R2 Service Pack 1 6.1.7601.28117; Microsoft Windows Server 2008 Service Pack 2 6.0.6003.23717; Microsoft Windows Server 2012 6.2.9200.25868; Microsoft Windows Server 2012 R2 6.3.9600.22968; Microsoft Windows Server 2016 10.0.14393.8783; Microsoft Windows Server 2019 10.0.17763.8276; Microsoft Windows Server 2022 10.0.20348.4648. Check the vendor advisory for mitigations.

References

https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-20833

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