SQL Server 2025 CU6 Serious Defect

Question

SQL Server 2025 CU6 Serious Defect

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SQL Server 2025 CU6 lists Linked Servers as a "Known Issue" - the workarounds are terrible - this needs fixing urgent.

To summarise, users will get "Access to the remote server is denied because no login-mapping exists." when trying to use a linked server, even when the linked server is configured to use the current users context (useself=true).

The workarounds are to make that user a sysadmin (lol), remove use of provstr (which is VERY painful if you're just pointing to an internal SQL server that does not use encryption etc), or to add UID to the provstr (which makes ZERO sense when using useself=true).

Also, their Known Issue lists this as a fault with MSDASQL - again, that's not true as it also occurs with "SQLNCLI" which SSMS 22 still uses as default when selecting "SQL Server" as the "Server Type"

How do we escalate this with Microsoft or at least get better workarounds or ETA's on fix?

Erland Sommarskog 135.6K Reputation points MVP Volunteer Moderator

2026-07-13T21:21:01.1366667+00:00

If you give details how you are trying to set up your linked server, we may be able to help you. Preferably, by showing the calls to sp_addlinkedserver and sp_addlinkedsrvlogin. (The UI is more confusing than helpful in my opinion.)

Yes, it is a little more work to set up a linked server in SQL 2025 if you do not have trusted certificates in place, but it's not insurmountable.

1 answer

Your answer

Erland Sommarskog 135.6K Reputation points MVP Volunteer Moderator

2026-07-13T21:21:01.1366667+00:00

If you give details how you are trying to set up your linked server, we may be able to help you. Preferably, by showing the calls to sp_addlinkedserver and sp_addlinkedsrvlogin. (The UI is more confusing than helpful in my opinion.)

Yes, it is a little more work to set up a linked server in SQL 2025 if you do not have trusted certificates in place, but it's not insurmountable.

Answer 1

Bruce (SqlWork.com) 84,501

The issue is SqlServers increased security has broken some old drivers. The drivers would need to be updated to support the new security. MSDASQL has long been depreciated and SQL Native client support ends tomorrow, so it’s not likely to be fixed.

the true fix is to upgrade to supported drivers. Change the driver used for the linked server to a supported driver.

Note: SSMS hasn’t included the SQLNCLI driver since version 19.

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