SQL Server 2025 Release Notes

Known issues in this update

Incorrect behavior of SESSION_CONTEXT in parallel plans
Queries that use the built-in SESSION_CONTEXT function might return incorrect results or trigger access violation (AV) dump files when run in parallel query plans. This issue occurs because of the manner in which SESSION_CONTEXT interacts with parallel execution threads, particularly if the session is reset for reuse.
For more information, see the Known issues section in SESSION_CONTEXT.

Improvements and fixes included in this update

A downloadable Microsoft Excel workbook that contains a summary list of builds, together with their current support lifecycle, is available. The Excel file also contains detailed fix lists for SQL Server 2025, SQL Server 2022, SQL Server 2019, and SQL Server 2017. Download this Excel file now.

Note
Individual entries in the following table can be referenced directly through a bookmark. If you select any bug reference ID in the table, a bookmark tag is added to the URL by using the "#NNNNNNN" format. You can then share this URL with others so that they can jump directly to the desired fix in the table.

For more information about the bugs that are fixed and enhancements that are included in this cumulative update, see the following table.

Improvements and fixes included in this update:

• Bug reference 4838699: Fixes an issue that causes StripedVdi tests to fail if the Sqlvdi.dll file isn't registered on running instances. Fix area: SQL Server Engine, Backup Restore, Platform: Windows
• Bug reference 4860948: For cluster_type = NONE or EXTERNAL, availability group (AG) properties exist on only the local replica. This update writes the properties to the AG configuration so that all AG replicas receive the same properties. Fix area: SQL Server Engine, High Availability and Disaster Recovery, Platform: All
• Bug reference 4869015: Fixes a potential inaccuracy in resource governor accounting for the tempdb space if accelerated database recovery is enabled for tempdb. Fix area: SQL Server Engine, Resource Governor, Platform: All
• Bug reference 4924793: Fixes an issue in which an assertion and a dump file are generated around midnight on New Year’s Day during an operation that accesses Azure Blob Storage. Fix area: SQL Server Engine, Storage Management, Platform: All
• Bug reference 4925942: Fixes an issue that triggers nonyielding scheduler dump files in PmmLogAcceptBlock on the availability group (AG) secondary replica. The issue occurs if the persistent log buffer is enabled, and the database log cache contains primarily tiny log records. Fix area: SQL Server Engine, Log Management, Platform: All
• Bug reference 4931611: Fixes an issue in which the distributor is part of an availability group (AG) and uses case-sensitive (_CS) collation. The distribution agent incorrectly uses the AG primary replica name instead of AG listener name. Fix area: SQL Server Engine, Replication, Platform: All

How to obtain or download this CU or the latest CU package

File information

Notes for this update

How to uninstall this update

References

This article describes the updates to the SQL Server incremental servicing model (ISM) for SQL Server 2017 as they relate to the Service Pack (SP) policy. For more information about the changes to the SQL Server ISM, see An Incremental Servicing Model is available from the SQL Server team to deliver hotfixes for reported problems.

Note

Earlier versions of SQL Server are not affected by this SP policy change. Service Packs (SPs) will continue to be provided for the reminder of mainstream support for SQL Server 2014 and SQL Server 2016.

The Modern Servicing Model (MSM)

Starting from SQL Server 2017:

• SPs will no longer be available. Only Cumulative Updates (CUs) and critical updates (GDRs) will be provided.

• CUs will contain localized content if it's necessary as what SPs have done.

• CUs will be delivered more frequently at first and then less frequently: every month for the first 12 months, and then every quarter for the final four years of the five-year mainstream lifecycle.

Note

The MSM only applies to SQL Server 2017 and later versions.

FAQ

• Q:
  SPs were fully localized, and one update file was released for every supported language. How will this work with only CUs?

• A:
  CUs will be localized starting from SQL Server 2017, and they will handle this requirement and continue only releasing a single language-agnostic update file.

• Q:
  Microsoft provided "slipstream" packages (RTM+SPn in a single media package) at each SP at approximately yearly intervals. How will this work without SPs?

• A:
  CU based slipstream media will be provided at approximately yearly intervals. For example, when CU12 for SQL Server 2017 is released, the slipstream media that has SQL Server 2017 CU12 preinstalled is also provided.

• Q:
  Previously, when SP2 was released, for example, an instance on the RTM baseline would have to be upgraded to SP1 or SP2 to receive a hotfix. How will this work without SPs?

• A:
  Without SPs, the only baseline will be RTM, and it will receive CUs for five years. There's no minimum servicing level requirement to receive CUs any longer.

• Q:
  Is the SQL Server lifecycle policy affected because there are no SPs any longer?

• A:
  No, the servicing lifecycle has not changed from SQL Server 2016 as it relates to mainstream and extended support.

References

• KB 935897
  An Incremental Servicing Model is available from the SQL Server team to deliver hotfixes for reported problems

• KB 3177534
  How to obtain the latest SQL Server 2016 service pack

• KB 2958069
  How to obtain the latest SQL Server 2014 service pack

• KB 2755533
  How to obtain the latest SQL Server 2012 service pack

• KB 2527041
  How to obtain the latest SQL Server 2008 R2 service pack

• KB 968382
  How to obtain the latest SQL Server 2008 service pack

• Microsoft SQL Server support lifecycle

• KB 321185
  How to determine the version and edition of SQL Server and its components

• The script to determine which version and edition of SQL Server Database Engine is running.

• KB 957826
  The builds for all SQL Server versions

• KB 822499
  Naming schema and Fix area descriptions for SQL Server software update packages

• KB 824684
  Description of the standard terminology that is used to describe Microsoft software updates

Summary

Important

This update is temporarily unavailable for download because of a known issue related to Database Mail.

This article describes Cumulative Update package 1 (CU1) for Microsoft SQL Server 2025. This update contains 16 fixes that were issued after the initial release of SQL Server 2025. It updates components in the following builds:

• SQL Server - Product version: 17.0.4005.7, file version: 2025.170.4005.7
• Analysis Services - Product version: 17.0.25.223, file version: 2025.170.25.223

Known issues in this update

Database Mail stops working after updating

Database Mail stops working after you install this cumulative update. You might see the following error message:
Could not load file or assembly 'Microsoft.SqlServer.DatabaseMail.XEvents, Version=17.0.0.0, Culture=neutral, PublicKeyToken=89845dcd8080cc91' or one of its dependencies. The system cannot find the file specified.
If you use Database Mail and already downloaded this update, don't install it until a fix is available.
If you already installed this update, uninstall it to restore Database Mail functionality.

Incorrect behavior of SESSION_CONTEXT in parallel plans

Queries that use the built-in SESSION_CONTEXT function might return incorrect results or trigger access violation (AV) dump files when run in parallel query plans. This issue occurs because of the manner in which SESSION_CONTEXT interacts with parallel execution threads, particularly if the session is reset for reuse.
For more information, see the Known issues section in SESSION_CONTEXT.

Improvements and fixes included in this update

A downloadable Microsoft Excel workbook that contains a summary list of builds, together with their current support lifecycle, is available. The Excel file also contains detailed fix lists for SQL Server 2025, SQL Server 2022, SQL Server 2019, and SQL Server 2017. Download this Excel file now.

Note

Individual entries in the following table can be referenced directly through a bookmark. If you select any bug reference ID in the table, a bookmark tag is added to the URL by using the "#NNNNNNN" format. You can then share this URL with others so that they can jump directly to the desired fix in the table.

For more information about the bugs that are fixed and enhancements that are included in this cumulative update, see the following table.

[Table of Improvements and fixes included in this update with bug references and descriptions]

How to obtain or download this or the latest cumulative update package

File information

Notes for this update

How to uninstall this update

References

• Announcing updates to the SQL Server Incremental Servicing Model (ISM)
• SQL Server Service Packs are no longer supported starting from SQL Server 2017
• Determine which version and edition of SQL Server Database Engine is running
• Servicing models for SQL Server
• Naming schema and Fix area descriptions for SQL Server software update packages
• Description of the standard terminology that is used to describe Microsoft software updates

Last updated on 01/20/2026

This security update contains fixes and resolves vulnerabilities

To learn more about the vulnerabilities, see the following security advisories:

■ CVE-2026-20803 - Microsoft 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: 17.0.1050.2, file version: 2025.170.1050.2

Improvements and fixes included in this update

A downloadable Microsoft Excel workbook that contains a summary list of builds, together with their current support lifecycle, is available. The Excel file also contains detailed fix lists. Download this Excel file now.

Note: Individual entries in the following table can be referenced directly through a bookmark. If you select any bug reference ID in the table, a bookmark tag is added to the URL by using the "#bkmk_NNNNNNN" format. You can then share this URL with others so that they can jump directly to the desired fix in the table.

| Bug reference | Description | Fix area | Component | Platform |
| 4836807 | Restricts privileges for the DBCC stackdump so that only the sysadmin can invoke the dump file. | SQL Server Engine | Security Infrastructure | Linux, Windows |

How to obtain and install the update

• Method 1: Windows Update

• Method 2: Microsoft Update Catalog

• Method 3: Microsoft Download Center

More information

Prerequisites

Security update deployment information

File hash information

File information

The English version of this package has the file attributes (or later file attributes) that are listed in the following worksheet. The dates and times for these files are listed in Coordinated Universal Time (UTC). When you view the file information, it is converted to local time. To find the difference between UTC and local time, use the Time Zone tab in the Date and Time item in Control Panel.

For all supported x64-based versions - Download the list of files that are included in security update 5073177.

Information about protection and security

Protect yourself online: Windows Security support

Learn how we guard against cyber threats: Microsoft Security