Monstra CMS through 3.0.4 has an incomplete "forbidden types" list that excludes .php (and similar) file extensions but not the .pht or .phar extension, which allows remote authenticated Admins or Editors to execute arbitrary PHP code by uploading a file, a different vulnerability than CVE-2017-18048.
Monstra CMS 3.0.4 allows users to upload arbitrary files, which leads to remote command execution on the server, for example because .php (lowercase) is blocked but .PHP (uppercase) is not.
Monstra 3.0.1 and earlier uses a cookie to track how many login attempts have been attempted, which allows remote attackers to conduct brute force login attacks by deleting the login_attempts cookie or setting it to certain values.