Language: PHP
Label: vulnerable
CWE: CWE-79 \u2014 Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users.

Code:
    public function addHint($hint, $important = false)
    {
        if (!empty($hint)) {
            if ($important) {
                $this->important = true;
                $this->hints[] = error($hint, true);
            } else {
                $this->hints[] = info($hint, true);
            }
        }
    }