Purity: Impurity on the Kafan

Practical Laws of Islam as per the teachings of Ayatullah Sistani

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.

-Ayatullah Sistani, Practical Laws of Islam, Purification (Taharah)