Venable's move was made Saturday and is retroactive to Friday. Venable is hitting .238 with eight home runs and 32 RBIs.
Cunningham is up for the second time. He hit .290 (9 for 31) with one homer and four RBIs in 13 games during his first stint before being optioned on July 1.
He hit a grand slam for his first hit with the Padres on June 15. Cunningham played parts of the last two seasons for Oakland.