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CVE-2021-36942: Windows LSA Spoofing Vulnerability

• Severity: medium (CVSS 5.0 v2.0)
• Exploited in the wild: yes — in CISA KEV since 2021-11-03
• EPSS: 66.0% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2021-08-12 · updated 2026-08-10

Description

Windows LSA Spoofing Vulnerability

Affected products

• Microsoft Windows Server 2004: before 10.0.19041.1165 — fixed in 10.0.19041.1165
• Microsoft Windows Server 2008: r2-sp1
• Microsoft Windows Server 2012: r2
• Microsoft Windows Server 2016: before 10.0.14393.4583 — fixed in 10.0.14393.4583
• Microsoft Windows Server 2019: before 10.0.17763.2114 — fixed in 10.0.17763.2114
• Microsoft Windows Server 20H2: before 10.0.19042.1165 — fixed in 10.0.19042.1165
• Microsoft Windows Server 2008 R2 Service Pack 1: from 6.1.7601.0 before 6.1.7601.25685 — fixed in 6.1.7601.25685
• Microsoft Windows Server 2008 Service Pack 2: from 6.0.6003.0 before 6.0.6003.21192 — fixed in 6.0.6003.21192
• Microsoft Windows Server 2012: from 6.2.9200.0 before 6.2.9200.23435 — fixed in 6.2.9200.23435
• Microsoft Windows Server 2012 R2: from 6.3.9600.0 before 6.3.9600.20094 — fixed in 6.3.9600.20094
• Microsoft Windows Server 2016: from 10.0.14393.0 before 10.0.14393.4583 — fixed in 10.0.14393.4583
• Microsoft Windows Server 2019: from 10.0.17763.0 before 10.0.17763.2114 — fixed in 10.0.17763.2114
• Microsoft Windows Server version 2004: from 10.0.0 before 10.0.19041.1165 — fixed in 10.0.19041.1165
• Microsoft Windows Server version 20H2: from 10.0.0 before 10.0.19042.1165 — fixed in 10.0.19042.1165

How to fix

Upgrade to a fixed version: Microsoft Windows Server 2004 10.0.19041.1165; Microsoft Windows Server 2016 10.0.14393.4583; Microsoft Windows Server 2019 10.0.17763.2114; Microsoft Windows Server 20H2 10.0.19042.1165; Microsoft Windows Server 2008 R2 Service Pack 1 6.1.7601.25685; Microsoft Windows Server 2008 Service Pack 2 6.0.6003.21192; Microsoft Windows Server 2012 6.2.9200.23435; Microsoft Windows Server 2012 R2 6.3.9600.20094; Microsoft Windows Server 2016 10.0.14393.4583; Microsoft Windows Server 2019 10.0.17763.2114; Microsoft Windows Server version 2004 10.0.19041.1165; Microsoft Windows Server version 20H2 10.0.19042.1165. Check the vendor advisory for mitigations.

References

• https://msrc.microsoft.com/update-guide/vulnerability/CVE-2021-36942
• https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-36942
• https://www.kb.cert.org/vuls/id/405600
• https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-36942

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