72 Pa. Stat. § 5884
The title to any real estate, situate in this Commonwealth, which was acquired at a tax sale or a sale on a judgment for a tax claim prior to January 1, 1948, by the county commissioners, any taxing district or trustee for any taxing district, which title has been heretofore purchased in redemption by the prior owner, his heirs or legal representatives or any lien creditor, his heirs, assigns or legal representative or other person interested redeeming the property for the benefit of the prior owner, is hereby declared to be good and valid and free and clear of any cloud on such title due to the act of July 7, 1947 (P.L. 1368), known as the "Real Estate Tax Sale Law", and its amendments, and such purchaser as aforesaid and his heirs, successors and assigns shall hold and may convey such title and estate indefeasible as to any right which may have arisen by reason of said unauthorized holding and conveyance by such county commissioners, taxing district or trustee for a taxing district and all such conveyances heretofore made are hereby ratified and confirmed.
72 P.S. § 5884