The hosts found themselves on the back foot early on as Eoin Doyle fired a warning shot with five minutes on the clock, Joe Lewis springing into action to parry the ball clear.
The early warning went unheeded and managerless Fulham found themselves trailing five minutes later when Joe Garner popped up at the back post unmarked and headed home.
Fulham struggled to create clear-cut chances in the first half but were almost level on the half-hour mark when Moussa Dembele's curling effort was tipped over the bar by Jason Pickford.
The hosts felt that they should have been awarded a penalty in the 56th minute when James Husband went down under Tom Clarke's challenge in the box, but the referee waved away their protests.
Preston defended tightly, but Fulham came close to an equaliser in the 69th minute when Tom Cairney shot on the turn, forcing Pickford to tip his effort over the bar.
The home side were much improved in the second period and they netted a deserved leveller in the 77th minute when McCormack hit an inch-perfect free kick into the top corner.
There was bad news for Preston in stoppage time as Stevie May was stretchered off with what looked like a serious injury following a challenge by Richard Stearman, leaving the field to a round of applause.
The result leaves Preston in 18th position in the table, four points behind Fulham in 13th.