ImpressCMS before 1.4.3 has Incorrect Access Control because include/findusers.php allows access by unauthenticated attackers (who are, by design, able to have a security token).
https://packetstormsecurity.com/files/166403/ImpressCMS-1.4.2-Incorrect-Access-Control.html
https://hackerone.com/reports/1081137