Nagios XI versions prior to 2024R1.1.3 contain a cross-site scripting (XSS) vulnerability in the Executive Summary Report component. This flaw arises from insufficient validation or escaping of user-supplied input, allowing attackers to inject and execute arbitrary scripts in the context of a victim's browser. The vulnerability has a medium severity rating with a CVSS score of 5.4. No known exploits in the wild have been reported, and no explicit patch information is provided in the source data.