From the age of 7 he received cello lessons, first privately, then at the music conservatory in Budapest. At the same time, Liebner began studying chamber music and composition with László Lajtha and subsequently at the Paris Conservatory with Maurice Marechal, Pierre Fournier, Paul Tortelier and Joseph Calvet.
From 1947 to 1985 Liebner was solo cellist at the Budapest Philharmonic and State Opera, solo cellist with the Hungarian Radio Symphony Orchestra, as well as at the German State Opera in Berlin, where he also worked as a dramaturge for six years. From 1969 Liebner was solo cellist with the Bruckner Orchestra in Linz and the ORF Chamber Orchestra.
