Symptoms
After you enable Basic Authentication mode for Microsoft SQL Server 2016 or 2017 Reporting Services (SSRS), you find that memory usage keeps growing, and this finally causes a memory spike in the LSASS.EXE process.
Resolution
This issue is fixed in the following cumulative updates for SQL Server:
Each new cumulative update for SQL Server contains all the hotfixes and all the security fixes that were included with the previous cumulative update. Check out the latest cumulative updates for SQL Server:
Status
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.
References
Learn about the terminology that Microsoft uses to describe software updates.