MISP contains a reflected cross-site scripting (XSS) vulnerability in the attribute histogram view. The $selectedTypes variable, which is derived from the URL path segment , was interpolated directly into a JavaScript array literal inside an onClick HTML attribute without any encoding or escaping. An attacker who can cause an authenticated MISP user to visit a crafted URL containing a malicious type value can execute arbitrary JavaScript in the victim's browser within the MISP application origin. Successful exploitation allows the attacker to read session cookies, perform actions on behalf of the victim, or exfiltrate sensitive data accessible from the MISP interface.  The vulnerability requires the victim to be authenticated and to actively navigate to the attacker-supplied URL.