United, with just three wins all season, defended in depth in the first half as they played into the teeth of a near gale, but it was a different story after the break.
Substitute Stuart Wardley struck the woodwork in the 47th minute and the U's then dominated the second period. However, they failed to penetrate Mansfield's in-form makeshift defence that, despite missing four first-team regulars, held on to record their fifth clean sheet in six games.
The Stags, beaten just once in five matches, were in trouble straight from the kick-off. Darren Quinton's clever ball over the top of the defence found John Turner sprinting clear, but the Cambridge striker's final shot was superbly turned past the post by the flying Kevin Pilkington.
Alex Baptiste then blocked Jermaine Easter's drive after first giving the ball away as the home side could have been two goals down in the first four minutes.
Mansfield recovered and Wayne Corden and Simon Brown both went close from distance, while Adam Murray and Alex Neil blazed well wide as the home side appeared to have a shoot on sight tactic in the very blustery conditions.
Another long-range blockbuster, this time from Jake Buxton, finally forced Cambridge keeper John Ruddy into a save on the half-hour.
Colin Larkin then glanced a Neil cross narrowly over and Murray flashed a 20-yard drive into the side-netting as the Stags continued to dominate the first half.
Cambridge, with the wind at their backs after half-time, almost snatched the lead when Wardley's mistimed shot through a crowded penalty area finally struck the post before Buxton hacked the ball to safety.
Within 30 seconds the home side had squandered an equally good chance at the other end when Buxton's fierce shot from an acute angle was excellently blocked by the diving Ruddy.
But neither side could break the deadlock as the points were eventually shared.