An Islamic loan for bad credit would in theory be aimed at a borrower whose credit score is bad to allow him to access funding that is in accordance with Islamic Sharia.
Halal financing with a poor credit score is a pure contradiction of Islamic finance which rejects any over-indebtedness based on usurious interest rates prohibited by Islamic sharia.
The very principle of Islamic finance is to prevent a borrower from becoming over-indebted by accumulating debts or by replacing debts with new financing.
In the event that a Muslim borrower faces a bad credit score, he will first have to clean up his financial situation before applying for financing based on Islamic finance.