Born in the Volhynian village of Przebraze, he worked as a forester, when in September 1939 the Red Army invaded eastern Poland. Cybulski was forcibly deported by the Soviets to Siberia on 10 February 1940. In the summer of 1940 he managed to escape and, after walking for eight weeks, returned to Volhynia. As he later wrote, his sports experiences in long-distance running were a great help. Upon coming back, he took up several menial jobs, trying to lie low and not to attract attention of Soviet authorities.