Mass. Gen. Laws ch. 204, § 20: Adverse claims to title

Section 20. If the validity of a sale is drawn in question by a person claiming adversely to the title of the deceased or of the ward, or under a title not derived from or through the deceased or the ward, the sale shall not be void by reason of any irregularity in the proceedings, if the executor, administrator, guardian, conservator or trustee was licensed to make the sale by a court of competent jurisdiction and executed and acknowledged in legal form a deed of the property.