There is no "current season".
Cinemax produced 3 seasons and finally ran the original season (they called it "Strike Back : origins") which ran 6 episodes and was an honest-to-goodness prequel to the Cinemax stuff. So, you have a total of 4 "seasons"... Origins + 3 Cinemax.
The final Cinemax season is scheduled for 10 episodes, but production has stopped due to the injury to Stapleton. The final season was scheduled to start airing later this year but seems likely to get pushed to 2015 due to the production hiatus.