The World Federation One Stop Fiqh

Ruling 570

If the kafan of a corpse becomes impure with an impurity – irrespective of whether the impurity was from the corpse itself or something else – then, in the event that the kafan would not be destroyed, the impure part must be washed or cut out even if this takes place after the corpse has been placed in the grave; and if washing or cutting it out is not possible but it is possible to replace the kafan, then it must be replaced.