Going for Hajj when one still owes mortgage payments


My parents have taken out a mortgage for a house sometime ago, they are currently paying interest on this loan. But now they have decided to go on Hajj, they still have 15 years left on the loan. Is it permissible for them to go on Hajj even though they owe money? Or will they have to wait 15 years first? Can they in the meantime do Umrah if it is not permissible to do Hajj?