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CVE-2021-42278: Active Directory Domain Services Elevation of Privilege Vulnerability

• Severity: medium (CVSS 6.5 v2.0)
• Exploited in the wild: yes — in CISA KEV since 2022-04-11
• EPSS: 73.3% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2021-11-10 · updated 2026-08-19

Description

Active Directory Domain Services Elevation of Privilege Vulnerability

Affected products

• Microsoft Windows Server 2004: before 10.0.19041.1348 — fixed in 10.0.19041.1348
• Microsoft Windows Server 2008: r2-sp1
• Microsoft Windows Server 2012: r2
• Microsoft Windows Server 2016: before 10.0.14393.4770 — fixed in 10.0.14393.4770
• Microsoft Windows Server 2019: before 10.0.17763.2300 — fixed in 10.0.17763.2300
• Microsoft Windows Server 2022: before 10.0.20348.350 — fixed in 10.0.20348.350
• Microsoft Windows Server 20H2: before 10.0.19042.1348 — fixed in 10.0.19042.1348
• Microsoft Windows Server 2008 R2 Service Pack 1: from 6.1.7601.0 before 6.1.7601.25769 — fixed in 6.1.7601.25769
• Microsoft Windows Server 2008 Service Pack 2: from 6.0.6003.0 before 6.0.6003.21282 — fixed in 6.0.6003.21282
• Microsoft Windows Server 2012: from 6.2.9200.0 before 6.2.9200.23517 — fixed in 6.2.9200.23517
• Microsoft Windows Server 2012 R2: from 6.3.9600.0 before 6.3.9600.20174 — fixed in 6.3.9600.20174
• Microsoft Windows Server 2016: from 10.0.14393.0 before 10.0.14393.4770 — fixed in 10.0.14393.4770
• Microsoft Windows Server 2019: from 10.0.17763.0 before 10.0.17763.2300 — fixed in 10.0.17763.2300
• Microsoft Windows Server 2022: from 10.0.20348.0 before 10.0.20348.350 — fixed in 10.0.20348.350
• Microsoft Windows Server version 2004: from 10.0.0 before 10.0.19041.1348 — fixed in 10.0.19041.1348
• Microsoft Windows Server version 20H2: from 10.0.0 before 10.0.19042.1348 — fixed in 10.0.19042.1348

How to fix

Upgrade to a fixed version: Microsoft Windows Server 2004 10.0.19041.1348; Microsoft Windows Server 2016 10.0.14393.4770; Microsoft Windows Server 2019 10.0.17763.2300; Microsoft Windows Server 2022 10.0.20348.350; Microsoft Windows Server 20H2 10.0.19042.1348; Microsoft Windows Server 2008 R2 Service Pack 1 6.1.7601.25769; Microsoft Windows Server 2008 Service Pack 2 6.0.6003.21282; Microsoft Windows Server 2012 6.2.9200.23517; Microsoft Windows Server 2012 R2 6.3.9600.20174; Microsoft Windows Server 2016 10.0.14393.4770; Microsoft Windows Server 2019 10.0.17763.2300; Microsoft Windows Server 2022 10.0.20348.350. Check the vendor advisory for mitigations.

References

• https://msrc.microsoft.com/update-guide/vulnerability/CVE-2021-42278
• https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-42278
• https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-42278

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