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.
The fix replaces the unsafe raw PHP loop that concatenated type values into a JavaScript array literal with a call to json_encode() using the JSON_HEX_TAG, JSON_HEX_APOS, JSON_HEX_QUOT, and JSON_HEX_AMP flags. This ensures that all special characters (angle brackets, quotes, ampersands) in the type values are hex-encoded, preventing any value from breaking out of the JavaScript string/array context and injecting arbitrary script.