The Wales international sustained the injury in the Bulls' 23-10 Stobart Super League defeat to Warrington on Saturday and has been told he needs an operation to pin the finger.
Bradford football manager Stuart Duffy said: "Craig has been in fine form this season and to lose him for such a long period is very disappointing for both Craig and the club."
Rugby League
O'Brien joins Widnes
05/03/2012 AT 11:46
Kopczak joins fellow forwards Olivier Elima, Ian Sibbit, James Donaldson and Chev Walker, as well as scrum-half Luke Gale, on the club's injury list just five weeks into the season.
Engage Super League
Giants too strong for Hull, Dragons crush Vikings
16/03/2013 AT 20:48
Engage Super League
Youngquest stars for Tigers
07/05/2012 AT 20:32