Microsoft SQL Server SQL Server 2025 Update Version 17.0.4055.5

KB5093421 delivers Cumulative Update 6 for Microsoft SQL Server 2025 with 19 fixes since CU5. It also updates bcp for vector data types and strict TLS options, and includes security guidance to enable Extended Protection on Windows.

• Security guidance: enable encryption with Extended Protection on SQL Server for Windows.
• Fixes handling of zero-length TLS records in the SNI SSL provider.
• Adds -H (HostNameInCertificate) and -J (ServerCertificate) options to bcp for strict TLS certificate validation.

• Fixes resource exhaustion and performance degradation during parallel vector index builds.
• Fixes memory access violations when altering a disabled DDL trigger.
• Fixes file creation failures on file systems that do not support hard links.
• Updates the Pacemaker resource agent to treat a forwarder replica as the local primary for the local availability group orchestrator.
• Fixes Error 17750 (DLL load failure) when running sp_executesql in a Linux container with Korean_Wansung_CI_AS collation.
• Fixes failures on Linux striped backups with 16 or more stripes when Transparent Huge Pages is enabled.
• Adds more detailed Windows Failover Cluster logging when the availability group resource DLL cannot retrieve diagnostic column information.
• Fixes a scheduling issue that could prevent a thread from suspending during an index rebuild.
• Changes the default FULLTEXT_INDEX_VERSION database scoped configuration to 2 on Azure SQL Managed Instance.
• Fixes date conversion errors during DDL operations on Change Data Capture tables.
• Updates bcp to support bulk import and export of vector(16) and vector(32) data types.
• Fixes inaccurate tempdb space usage accounting in uncommon cases.
• Upgrades SSIS password-based encryption for SQL Server 2025 packages to PBKDF2 with SHA-256 and 100,000 iterations.
• Fixes a failed assertion related to thread trace elements on the primary replica of an availability group.
• Fixes SSIS package deployment and execution failures when connecting to instances configured with Encrypt=Strict.
• Fixes possible failures on DML inserts of a NULL JSON document into a JSON index column.

• bcp now supports bulk import and export of vector(16) and vector(32) data types.
• bcp adds -H and -J options for strict TLS certificate validation.
• SSIS password-based encryption for SQL Server 2025 packages now uses PBKDF2 with SHA-256 and 100,000 iterations.
• The default FULLTEXT_INDEX_VERSION database scoped configuration is changed to 2 on Azure SQL Managed Instance.

• Queries using SESSION_CONTEXT in parallel plans may return incorrect results or trigger access violation dumps, especially after session reuse.
• Linked server queries using MSDASQL with a provider string may fail with error 7416 due to stricter connection validation.

• Packages saved after this update that target SQL Server 2025 require compatible SSDT and SSMS versions to open; packages targeting SQL Server 2022 and earlier are not affected.
• Support for vector(16) in bcp becomes functional only after the next ODBC driver release.
• For Windows, Microsoft recommends enabling encryption with Extended Protection.
• The update includes fixes for both Windows and Linux platforms, but some items apply only to one platform.

Product Information

Vendor: Microsoft

Product: SQL Server

Product type: Software

Variant: SQL Server 2025

Version: 17.0.4055.5

Vendor information published: Jun 17, 2026

Original release notes: View on vendor site

Published on updatealert.io: Sep 29, 2026