Nagios XI < 5.6.11 Unauthenticated XSS and SSRF via Highcharts

Nagios XI versions prior to 5.6.11 contain unauthenticated vulnerabilities in the Highcharts local exporting tool. Crafted export requests could (1) inject script into exported/returned content due to insufficient output encoding (XSS), and (2) cause the server to fetch attacker-specified URLs (SSRF), potentially accessing internal network resources. An unauthenticated remote attacker can leverage these issues to execute script in a user's browser when the exported content is viewed and to disclose sensitive information reachable from the export server via SSRF.