An information disclosure vulnerability exists in the iConfig proxy request of Zabbix server 2.4.X. A specially crafted iConfig proxy request can cause the Zabbix server to send the configuration information of any Zabbix proxy, resulting in information disclosure. An attacker can make requests from an active Zabbix proxy to trigger this vulnerability.
https://talosintelligence.com/vulnerability_reports/TALOS-2017-0327
https://lists.debian.org/debian-lts-announce/2019/03/msg00010.html