FortiGate FortiOS through SSL VPN Web Portal contains a cross-site scripting vulnerability. The login redir parameter is not sanitized, so an attacker can inject arbitrary script in the browser of an unsuspecting user in the context of the affected site. This can allow the attacker to steal cookie-based authentication credentials and launch other attacks such as a URL redirect. Affected versions are 6.0.0 to 6.0.4, 5.6.0 to 5.6.7, and 5.4 and below.