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:
        foreach ($aIP as $piece) {
            if (!preg_match('#^[0-9a-fA-F]{4}$#s', sprintf('%04s', $piece))) {
                return false;
            }
        }