In Kibana versions before 7.12.0 and 6.8.15 a flaw in the session timeout was discovered where the xpack.security.session.idleTimeout setting is not being respected. This was caused by background polling activities unintentionally extending authenticated users sessions, preventing a user session from timing out.
https://discuss.elastic.co/t/elastic-stack-7-12-0-and-6-8-15-security-update/268125