CVE-2019-7620
Logstash versions before 7.4.1 and 6.8.4 contain a denial of service flaw in the Logstash Beats input plugin. An unauthenticated user who is able to connect to the port the Logstash beats input could send a specially crafted network packet that would cause Logstash to stop responding.
Source: CVE-2019-7620