Language: PHP
Label: safe
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:
    protected function backward(&$i, &$current)
    {
        if ($i === null) {
            $i = count($this->inputZipper->front) - 1;
        } else {
            $i--;
        }
        if ($i < 0) {
            return false;
        }
        $current = $this->inputZipper->front[$i];
        return true;
    }