This is extremely common, and one of the reasons that using SSN for credit reports is a horrible practice. The only way for someone to dispute the debts is to report their parents to the authorities, which is a horrible position to be in when you’re freshly 18. The real solution would be a simple age check, to verify if the person applying for the loan is actually 18. But that is apparently too difficult would prevent banks from saddling literal children with mountains of debt.