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CVE-2021-40469: Windows DNS Server Remote Code Execution Vulnerability

• Severity: medium (CVSS 6.5 v2.0)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 7.6% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2021-10-13 · updated 2026-06-17

Description

Windows DNS Server Remote Code Execution Vulnerability

Affected products

• Microsoft Windows Server 2008: r2-sp1
• Microsoft Windows Server 2012: r2
• Microsoft Windows Server 2016: 20h2, 2004
• Microsoft Windows Server 2019: all versions
• Microsoft Windows Server 2022: all versions
• Microsoft Windows Server 2008 R2 Service Pack 1: from 6.1.0 before 6.1.7601.25740 — fixed in 6.1.7601.25740
• Microsoft Windows Server 2008 Service Pack 2: from 6.0.0 before 6.0.6003.21251 — fixed in 6.0.6003.21251
• Microsoft Windows Server 2012: from 6.2.0 before 6.2.9200.23490 — fixed in 6.2.9200.23490
• Microsoft Windows Server 2012 R2: from 6.3.0 before 6.3.9600.20144 — fixed in 6.3.9600.20144
• Microsoft Windows Server 2016: from 10.0.0 before 10.0.14393.4704 — fixed in 10.0.14393.4704
• Microsoft Windows Server 2019: from 10.0.0 before 10.0.17763.2237 — fixed in 10.0.17763.2237
• Microsoft Windows Server 2022: from 10.0.0 before 10.0.20348.288 — fixed in 10.0.20348.288
• Microsoft Windows Server version 2004: from 10.0.0 before 10.0.19041.1288 — fixed in 10.0.19041.1288
• Microsoft Windows Server version 20H2: from 10.0.0 before 10.0.19042.1288 — fixed in 10.0.19042.1288

How to fix

Upgrade to a fixed version: Microsoft Windows Server 2008 R2 Service Pack 1 6.1.7601.25740; Microsoft Windows Server 2008 Service Pack 2 6.0.6003.21251; Microsoft Windows Server 2012 6.2.9200.23490; Microsoft Windows Server 2012 R2 6.3.9600.20144; Microsoft Windows Server 2016 10.0.14393.4704; Microsoft Windows Server 2019 10.0.17763.2237; Microsoft Windows Server 2022 10.0.20348.288; Microsoft Windows Server version 2004 10.0.19041.1288; Microsoft Windows Server version 20H2 10.0.19042.1288. Check the vendor advisory for mitigations.

References

• https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-40469
• https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-40469

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