Nagios XI versions prior to 2024R1.4.2 contain a remote code execution vulnerability in the Business Process Intelligence (BPI) component. Insufficient validation and sanitization of administrator-controlled BPI configuration parameters (notably bpi_logfile and bpi_configfile) allow an authenticated administrative user to cause the product to create or overwrite files within the webroot and subsequently edit them via the BPI configuration editor. When such files carry executable extensions and are served by the web application, arbitrary code may be executed in the context of the web application user. Successful exploitation results in arbitrary command execution with the privileges of the Nagios XI web application user and can be leveraged to gain further control of the underlying host operating system.