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CVE-2021-1636: Microsoft SQL Elevation of Privilege Vulnerability

• Severity: medium (CVSS 6.5 v2.0)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 6.7% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2021-01-12 · updated 2026-06-17
• Weakness: CWE-89

Description

Microsoft SQL Elevation of Privilege Vulnerability

Affected products

• Microsoft SQL Server: 2012-sp4, 2014-sp3, 2016-sp2, 2017, 2019
• Microsoft SQL Server 2012 for x64-based Systems Service Pack 4 (QFE): from 11.0.0 before publication — fixed in publication
• Microsoft SQL Server 2012 Service Pack 4 (QFE): from 11.0.0 before publication — fixed in publication
• Microsoft SQL Server 2014 Service Pack 3 (CU 4): from 12.0.0 before publication — fixed in publication
• Microsoft SQL Server 2014 Service Pack 3 (GDR): from 12.0.0 before publication — fixed in publication
• Microsoft SQL Server 2016 for x64-based Systems Service Pack 2 (GDR): from 13.0.0 before publication — fixed in publication
• Microsoft SQL Server 2016 Service Pack 2 (CU 15): from 13.0.0 before publication — fixed in publication
• Microsoft SQL Server 2017 (CU 22): from 14.0.0 before publication — fixed in publication
• Microsoft SQL Server 2017 (GDR): from 14.0.0 before publication — fixed in publication
• Microsoft SQL Server 2019 (CU 8): from 16.0.0 before publication — fixed in publication
• Microsoft SQL Server 2019 (GDR): from 15.0.0 before publication — fixed in publication

How to fix

Upgrade to a fixed version: Microsoft SQL Server 2012 for x64-based Systems Service Pack 4 (QFE) publication; Microsoft SQL Server 2012 Service Pack 4 (QFE) publication; Microsoft SQL Server 2014 Service Pack 3 (CU 4) publication; Microsoft SQL Server 2014 Service Pack 3 (GDR) publication; Microsoft SQL Server 2016 for x64-based Systems Service Pack 2 (GDR) publication; Microsoft SQL Server 2016 Service Pack 2 (CU 15) publication; Microsoft SQL Server 2017 (CU 22) publication; Microsoft SQL Server 2017 (GDR) publication; Microsoft SQL Server 2019 (CU 8) publication; Microsoft SQL Server 2019 (GDR) publication. Check the vendor advisory for mitigations.

References

• https://msrc.microsoft.com/update-guide/vulnerability/CVE-2021-1636
• https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-1636

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