CVE-2026-23919: Insufficient isolation of JavaScript (Duktape) execution context on Zabbix Server

For performance reasons Zabbix Server/Proxy reuses JavaScript (Duktape) contexts (used in script items, JavaScript reprocessing, Webhooks). This can lead to confidentiality loss where a regular (non-super) Zabbix administrator leaks data for hosts they do not have access to. A fix has been released that makes the built in Zabbix JavaScript objects read-only, but please be advised that usage of global JavaScript variables is not recommended because their content could be leaked. More information <a href='https://www.zabbix.com/documentation/7.4/en/manual/installation/known_issues#preprocessing-global-variables-are-unsafe'>in Zabbix documentation</a>.