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SQL Server 2016 SP3 + GDR SQL Server 2016 SP3 + GDR Security update
Patch Tuesday

KB5077474

KB5077474: Security update for SQL Server 2016, GDR branch, March 2026. Merge replication privilege flaw fixed; Administrator login protected

In short

Fixes two important vulnerabilities in SQL Server 2016 SP3 GDR, including a publicly disclosed elevation-of-privilege flaw. It also blocks ALTER USER when the target is the system Administrator account.

Does it affect you? Applies to: Devices running SQL Server 2016 SP3 or a SQL Server 2016 SP3 GDR release. The listed package is for x64 systems.

Build
13.0.6480.4
Servicing branch
GDR
Security
2 fixed
Restart
Required

For servers on the GDR branch: they get security fixes only. Servers that install cumulative updates (CU branch) get a separate update. Which branch am I on?

What changes

Fixes 2 changes

Replication

  • The merge replication version-upgrade process no longer has the elevation-of-privilege vulnerability addressed by this update.1
    Fixes an elevation of privilege vulnerability in the version upgrade process for merge replication.

Security Infrastructure

  • The ALTER USER operation is blocked when the target login is the system Administrator account.2
    The hotfix blocks the ALTER USER operation if the target login is the system Administrator account.

Technical details

Data sheet · Security · Downloads · Components Click to collapse or expand

Data sheet

Released
2026-03-10
Classification
Security Updates
Type
Cumulative update
Servicing branch
GDR
Restart
Required
Replaces
KB5068401, KB5065226, KB5063762, KB5058718
+4 earlier KB5046855, KB5046063, KB5042207, KB5040946
Replaced by
KB5084821
VersionBuildChannel
2016 13.0.6480.4 General availability

Security

2 vulnerabilities fixed
2 important
VulnerabilitySeverityCVSS
CVE-2026-21262
Microsoft SQL Server Elevation of Privilege Vulnerability
 Important 8.8
CVE-2026-26115
SQL Server Elevation of Privilege Vulnerability
 Important 8.8

Downloads (Microsoft Update Catalog)

Package 2016
510.8 MB
sqlserver2016-kb5077474-x64.exe Main update · KB5077474 SHA-1: 7990ee24…683a63

Updated components

515 files changed since the previous update for the same versions.

Top changed componentsFiles
SQL Server Engine77
SQL Server Analysis Services3
SQL Server PolyBase1

Sources

Updated
Cited passages from Microsoft's official notes (2)
  1. 1. Fixes an elevation of privilege vulnerability in the version upgrade process for merge replication. support.microsoft.com
  2. 2. This hotfix blocks the ALTER USER operation if the target login is the system Administrator account. support.microsoft.com
Checked automatically: 8 of 8 checks passed, 2 quoted passages · compared with Microsoft's page on Sep 26, 2026
  • Quotes found in the official pages: passed
  • Numbers found in the sources: passed
  • Vulnerabilities from the dossier only: passed
  • Links to allowed domains only: passed
  • Every official change covered: passed
  • Readable plain text: passed
  • Changes confirmed by the file list: passed
  • Sources agree: passed

A second AI read the text against the sources: correctness 5/5, clarity 4/5, completeness 5/5. How we work

Published by The Update Bureau. Written with AI from Microsoft's own documents, checked by rules and a second AI. How we work · Report a mistake