We have just upgraded several servers from some rather old versions to version 9.9.6 and stumbled across an issue.
If you try to log in using the client and enter an incorrect password twice then VisualCron stops responding and the server's CPU goes up to 100% with VisualCron hogging most of the CPU. The server becomes unresponsive and the only way to recover it is to kill the VisualCron service.
We have seen this happen on two live servers and can recreate it at will on a test server. We have tested on a server that hasn't yet been upgraded (version 8.2.9) and that does not exhibit this behaviour.
The servers in question are running Windows 2016.