Umbraco CMS Has Incomplete Server Termination During Explicit Sign-Out

Umbraco is a free and open source .NET content management system. In versions on the 13.x branch prior to 13.5.2 and versions on the 10.x branch prior to 10.8.7, during an explicit sign-out, the server session is not fully terminated. Versions 13.5.2 and 10.8.7 contain a patch for the issue.