The fix for CVE-2019-0199 was incomplete and did not address connection window exhaustion on write. By not sending WINDOW_UPDATE messages for the connection window (stream 0) clients were able to cause server-side threads to block eventually leading to thread exhaustion and a DoS.
When running on Windows with enableCmdLineArguments enabled, the CGI Servlet is vulnerable to Remote Code Execution due to a bug in the way the JRE passes command line arguments to Windows. The CGI Servlet is disabled by default. The CGI option enableCmdLineArguments is disabled by default in Tomcat 9.0.x (and will be disabled by default in all versions in response to this vulnerability).