When the script inevitably breaks or you encounter a problem, you have no one to turn to. You cannot submit a support ticket to the developer, and you certainly cannot ask for help in the legitimate community forums. You are completely on your own to diagnose and fix any issue, which can be a monumental task for a complex hosting panel.

If you want to offer hosting without high licensing costs, consider using free, actively maintained control panels instead of trying to hack VistaPanel:

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Detail the specific risks of SQL injection in nulled scripts.

Searching for "nulled" versions of the Vista Panel hosting script is strongly discouraged