If a customer’s Oracle or PostgreSQL connection count keeps climbing after Windows patching, check whether SQL Server is using an OLE DB linked server. Microsoft confirmed on November 11, 2026 that connections can stay open after the queries finish. Repeated queries can drive up connection counts and degrade performance.
Last verified November 13, 2026 UTC. Microsoft’s November 12 update on the Windows 11 26H2 release-health page includes that release in the affected list.
Where this applies
Check systems running SQL Server workloads that use linked-server queries through an OLE DB provider to reach an external database. Microsoft identifies Oracle and PostgreSQL among the affected targets. The issue starts with the October 13 Windows security updates and can persist on later updates. Compare the installed update on each SQL host with these starting points.
| Windows release | Originating October update | Build or release |
|---|---|---|
| Windows Server 2025 | KB5126646 | 26100.33650 |
| Windows Server 2022 | KB5126655 | 20348.5761 |
| Windows Server 2019 / version 1809 and Windows 10 1809 / Enterprise LTSC 2019 | KB5126651 | 17763.9376 |
| Windows Server 2016 | KB5126868 | 14393.9612 |
| Windows Server 2012 R2 ESU | KB5126836 | October monthly rollup |
| Windows Server 2012 ESU | KB5126835 | October monthly rollup |
| Windows 11 26H2, 25H2 and 24H2 | KB5127648 | 26300.9711, 26200.9711 and 26100.9711, respectively |
| Windows 11 26H1 | KB5127646 | 28000.3231 |
| Windows 11 23H2 | KB5126653 | 22631.7652 |
What to do across customer environments
Suggested MSP priority Expedite triage when external sessions are accumulating or production workloads are slowing. Add a representative linked-server query and connection-count check to the next patch validation for other applicable hosts.
Inventory the Windows build, SQL Server linked servers, OLE DB providers and target databases. Establish a normal session count on the destination database. On a degraded host, coordinate with the DBA to close identifiable idle sessions or restart the SQL service during an approved maintenance window. These steps can interrupt transactions and the connection buildup can recur.
Microsoft offers a mitigation through Support for business and says an out-of-band Windows update is planned. A fixed KB or build was unavailable in the guidance reviewed on November 13. When Microsoft publishes a fix for the installed Windows release, pilot it on an affected workload. Run repeated linked-server queries and confirm completed sessions release, connection counts return to baseline, and job runtimes and database health are stable.
Microsoft tracks this as a confirmed servicing regression. Its release-health notice gives no separate CVE, vendor severity, CVSS score or exploitation finding for it. CISA KEV has no separate entry or federal remediation deadline for this regression.
Official sources
Windows Server 2025 release health · Windows Server 2022 release health · Windows 11 26H2 release health · Microsoft Support for business