In August 1940, the MAK acquired the Cahn-Speyer collection of porcelain flasks, which had been declared expired, for 2,000 Reichsmarks. In 1947, 103 of the pieces were restituted to Dr. Paul Cahn-Speyer. Ten flasks remained at the MAK as loans for the time being, six of them were handed back to the collector in 1949. In 1953, Dr. Paul Cahn-Speyer sold the remaining four flasks to the museum for 8,500 Austrian Schillings as he was not granted an export license for them.
 

Due to the amendment of the Art Restitution Law in 2009, the Advisory Board reexamined the case of the four flasks on 7 March 2014 and advocated their restitution under the condition that the legal successors repaid the purchase price received in 1953.

So far, this restitution has not yet taken place.