A pair of second-half howlers by Carlisle goalkeeper Shamal George handed Stevenage a 2-0 win at Brunton Park.
The on-loan Liverpool keeper's error allowed Ben Kennedy to score Boro's opener and George gifted the second to Tom Pett.
Stevenage pressed the home defence well in the opening minutes and Kennedy went close to opening the scoring in the 10th minute when his 12-yard shot was blocked by George.
Former Rangers defender Clint Hill, making his home debut, twice went close with headers for Carlisle then it was the turn of Nicky Adams to hammer a right-foot drive from 20 yards which flew a fraction too high.
Stevenage opened the scoring in the 52nd minute when George failed to hold on to Joe Martin's corner kick from the left and Kennedy was first to react, prodding the ball home through a crowded area.
The bad dream turned into a nightmare for George on the hour mark when he failed to deal with an innocuous Pett header, allowing the ball to slip through his hands into the net to double Stevenage's lead.
Carlisle brought on their attacking substitutes but Boro's defence stayed resolute to frustrate the home side and see out the eight minutes of added time.