The Collaborative International Dictionary of English v.0.48:

Corruptness \Cor*rupt"ness\, n.
   The quality of being corrupt.
   [1913 Webster]

WordNet (r) 3.0 (2006):

corruptness
    n 1: the state of being corrupt
    2: lack of integrity or honesty (especially susceptibility to
       bribery); use of a position of trust for dishonest gain [syn:
       corruptness, corruption] [ant: incorruption,
       incorruptness]