None of them mention collateral but thanks, I learned something new
Not an expert on Islam law here (I'm not even Islam), but looks like there's a good explanation here complete with references:
https://islamqa.info/en/140078It pretty much said that it is indeed haram.
But. I think you can get a more clear answer from your local imam.
The website you mentioned is the first result on google when I research about collateral, it says that if I benefit from collateral it is counted as haram but what if i just get my money back by selling that collateral and send back the rest to the user who took the loan?
Hmm you got a point. Only scenario there is using the collateral and not selling it.
I think the first link provided by bestluck does have that scenario. Just look for the word "mortgage".
2317. * If the creditor demands the repayment of debt when it is due, and the debtor does not repay it, the creditor can sell the mortgaged property and collect his dues, provided that he had been authorized to do so. And if he was not authorized to do so, it will be necessary to obtain permission from the debtor. And if the debtor is not available, he should obtain permission for the sale of the property from the Mujtahid. In either case, if the sale proceeds exceed the amount due to him, he should give the amount in excess of his debt to the debtor.