When you die before paying off the mortgage on your property, the lender naturally retains the right to repayments on its secured loans. If you own your home as a joint-tenant (for example with your spouse or partner) and in this case, the property bypasses your estate and all obligations (including loan repayments) revert to the surviving joint-tenant.
In all other scenarios, the estate must find a way to pay the debt off to avoid the house having to be sold. Either the estate pays off the mortgage using any available funds, or a Beneficiary inherits the house and takes over future mortgage payments.