Stuart McKinstry scored twice in the first half to put Leeds in control, only for Benny Ashley-Seal, pictured, to pull a goal back for Wolves four minutes before half-time.
Luke Cundle made it 2-2 from a tight angle midway through the second half as Wolves moved on to seven points, five clear of fourth-placed Leeds.
Vale opened the scoring on the stroke of half-time before setting up Brennan to double Blackburn's advantage in the 69th minute.
Rovers are five points ahead of second-placed Middlesbrough. Palace sit fourth with one point.
See: Blackburn report