A regular Zabbix user can search other users in their user group via Zabbix API by select fields the user does not have access to view. This allows data-mining some field values the user does not have access to.

Zabbix Frontend provides a feature that allows admins to maintain the installation and ensure that only certain IP addresses can access it. In this way, any user will not be able to access the Zabbix Frontend while it is being maintained and possible sensitive data will be prevented from being disclosed. An attacker can bypass this protection and access the instance using IP address not listed in the defined range.

A regular Zabbix user with no permission to the Monitoring -> Problems view is still able to call the problem.view.refresh action and therefore still retrieve a list of active problems.