KB5077470 — Security Update for SQL Server 2019 GDR

Overview

KB5077470 is a critical security update for Microsoft SQL Server 2019 GDR released on March 10, 2026. This update addresses multiple high-severity vulnerabilities that could allow remote code execution, information disclosure, privilege escalation, and denial of service attacks on affected SQL Server instances.

Security Vulnerabilities Addressed

This update resolves several critical security vulnerabilities in SQL Server 2019:

Remote Code Execution Vulnerability

A critical vulnerability in the SQL Server query processing engine allows authenticated users to execute arbitrary code with SYSTEM privileges. This vulnerability has a CVSS score of 8.8 and affects all editions of SQL Server 2019 GDR. Attackers with database access could exploit this vulnerability to gain complete control over the SQL Server host system.

Information Disclosure Vulnerability

An information disclosure flaw allows low-privileged database users to access sensitive system metadata and schema information beyond their authorized scope. This vulnerability could enable attackers to perform reconnaissance and gather information for further attacks against the database infrastructure.

Privilege Escalation Vulnerability

A privilege escalation vulnerability in backup and restore operations could allow users with backup operator privileges to gain additional system-level permissions. This could lead to unauthorized access to system resources and potential compromise of the entire SQL Server environment.

Denial of Service Vulnerability

A denial of service vulnerability in connection handling could allow attackers to cause service interruption through specially crafted network requests, potentially making SQL Server instances unavailable to legitimate users.

Affected Systems

This security update applies to the following SQL Server configurations:

Installation Requirements

Before installing KB5077470, ensure the following prerequisites are met:

• Administrative privileges on the target system
• SQL Server 2019 GDR baseline installation
• Minimum 2 GB available disk space
• All SQL Server services stopped during installation
• Network connectivity for downloading the update package

Deployment Methods

Microsoft Update Catalog

Download the standalone installation package directly from Microsoft Update Catalog. This method is recommended for systems that require manual update deployment or are not connected to Windows Update services.

Windows Server Update Services

Enterprise environments can deploy this update through WSUS or System Center Configuration Manager. The update will be categorized under SQL Server products and can be targeted to specific computer groups.

Automatic Updates

Systems configured for automatic updates will receive this update through Microsoft Update. The installation will be scheduled according to the configured maintenance window settings.

Post-Installation Verification

After installing KB5077470, verify the installation using the following methods:

SQL Server Management Studio

Connect to the SQL Server instance and check the version information in the server properties dialog. The version should reflect the updated build number.

T-SQL Query

SELECT @@VERSION;

Execute this query to display the current SQL Server version and build information.

Windows Programs and Features

Check the installed updates list in Windows Programs and Features to confirm KB5077470 appears in the installed updates.

Security Recommendations

In addition to installing this security update, Microsoft recommends implementing the following security best practices:

• Regularly review and audit SQL Server user permissions
• Enable SQL Server audit logging for security-sensitive operations
• Implement network segmentation to limit SQL Server access
• Use Windows Authentication mode when possible
• Keep SQL Server Management Studio and client tools updated
• Monitor SQL Server error logs for suspicious activity

Impact Assessment

This security update may have the following impacts on SQL Server operations:

Performance Considerations

Temporary performance degradation may occur immediately after installation due to query plan cache clearing. Performance typically returns to baseline levels within 24 hours as SQL Server rebuilds optimized execution plans.

Application Compatibility

Applications should continue to function normally after this update. However, applications with very short connection timeouts may experience temporary connectivity issues during the first few hours after installation.

Maintenance Window Requirements

Plan for a maintenance window of 30-60 minutes to complete the installation and verify system functionality. Database services will be unavailable during the installation process.