KB5077464: hotfix blocks the ALTER USER operation if the target login is the system Administrator account.

KB5077464 - Description of the secBOLDurity update for SQL Server 2022 CU23: March 10, 2026

Summary
This security update contains fixes and resolves vulnerabilities. To learn more about the vulnerabilities, see the following security advisories:

• CVE-2026-21262 - SQL Server Elevation of Privilege Vulnerability​​​​​​​
• CVE-2026-26115 - SQL Server Elevation of Privilege Vulnerability

The Microsoft SQL Server components are updated to the following builds in this security update:

• SQL Server - product version: 16.0.4240.4, file version: 2022.160.4240.4

Improvements and fixes included in this update
A downloadable Excel workbook that contains a summary list of builds, together with their current support lifecycle, is available.

• 4945509: Fixes an elevation of privilege vulnerability in the version upgrade process for merge replication.
• 4934194: This hotfix blocks the ALTER USER operation if the target login is the system Administrator account.