pfSense contains a flaw that allows a persistent cross-site scripting (XSS) attack. This flaw exists because the application does not validate the XAUTH username upon submission to the diag_logs_ipsec.php script. This may allow an attacker to create a specially crafted login request that would be logged on the server. An administrator viewing the log via Status > System Logs > IPSec would then render the script code in their browser within the trust relationship between them and the server.