In Nagios XI 5.6.9, XSS exists via the nocscreenapi.php host, hostgroup, or servicegroup parameter, or the schedulereport.php hour or frequency parameter. Any authenticated user can attack the admin user.
Severity
CVSS 3.1
5.4 medium
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N
EPSS
26% chance of exploitation in the next 30 days; higher than 97% of CVEs (scores of 2026-10-31)