Update - 2018-09-26
This maintainer has fixed this security issue. Please install https://www.drupal.org/project/nucleus/releases/7.x-1.6 to fix the security issue
The security team is marking this theme unsupported. There is a known security issue with the theme that has not been fixed by the maintainer. If you would like to maintain this theme, please read: https://www.drupal.org/node/251466.
The security team marks all unsupported themes and modules critical by default.
If you use this theme, you should uninstall it.