Static code injection vulnerability in admin/configuration/modifier.php in zKup CMS 2.0 through 2.3 allows remote attackers to inject arbitrary PHP code into fichiers/config.php via a null byte (%00) in the login parameter in an ajout action, which bypasses the regular expression check.

zKup CMS 2.0 through 2.3 does not require administrative authentication for admin/configuration/modifier.php, which allows remote attackers to gain administrator privileges via a direct request, as demonstrated by adding a new administrator.