The 26-year-old has been out with a torn anterior cruciate knee ligament since October.
"The light is there at the end of the tunnel for him," BBC Sport quotes Mackay as saying. "He's back in training, which is great and he will hopefully get an under-21 game next week.
"If by Hull, which is two weeks away, Richard Collins in our physio department feels that he's ticked every box in our fitness department and I'm looking at him in training, that's absolutely a possibility."
Maynard joined Cardiff from West Ham United on a three-year contract last August.