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:
function pageSlug() {

    $URI = explode(root_domain(), rtrim($_SERVER['HTTP_HOST'].$_SERVER['REQUEST_URI'], "/"));
    $URI = explode("?", $URI[1]);
    return trim($URI[0], '/');

}