It was a late Sammie Szmodics goal that saw the U's take a share of the points, bundling the ball home at the far post.
John McGreal's side had to come behind though, with Gerry McDonagh opening the scoring after twenty minutes.
The U's have earned a point at Cambridge United in their latest away day.
McGreal stuck with the same starting eleven that were unlucky to lose at Grimsby in midweek, but there were two changes on the bench.
Szmodics returned for the first time following an ankle operation and Macauley Bonne came straight back into the squad after his loan spell at Woking.
Both teams had chances in the opening ten minutes with George Maris testing Sam Walker from twenty five yards, whilst Brennan Dickenson had an effort blocked from close range.
It was Cambridge who took the lead through Gerry McDonagh after he found himself in some space at the back post and smashed the ball past Walker with twenty minutes played.
The U’s replied well and created a good chance after Tarique Fosu played in Chris Porter but his effort was saved well by Norris.
Cambridge then had a goal ruled offside after Harrison Dunk bundled the ball past Walker but he was judged to be beyond the last U's man.
The U’s ended the first half strongly and had good spells of possession but couldn’t break down a resilient Cambridge back four.
Cambridge came out and started the second half brightly as Liam O’Neill looped a volley onto the roof of the U’s net with the first move from kick off.
The opening phases of the second half were played out with a sense of nervousness after O’Neills’ chance, but the U’s had the majority of the possession and were starting to knock on the door.
Rekeil Pyke replaced Tarique Fosu with sixty two minutes gone and almost made an immediate impact - but his headed effort was saved by Will Norris.
Luke Berry almost hit back immediately after finding himself in space at the back post, but his effort was comfortably gathered by Sam Walker.
With twenty minutes left, Chris Porter flicked on a Colchester corner and George Elokobi somehow fired an acrobatic effort at goal that was excellently saved by Will Norris.
With eighty one minutes on the clock, the newly introduced Macauley Bonne thought he’d drawn the U’s level after converting from close range, only to see his goal ruled out for offside.
Just a few moments later, the U’s were level after substitute Sammie Szmodics found himself in space at the back post and headed past Norris.
It was a welcome return to first team football for Szmodics, who hadn’t played in the first team since December after being ruled out with an ankle injury.
The U’s had some half chances in injury time through Bonne and Lapslie but the game ended in a draw which sees the U’s remain in ninth place on fifty one points, just three off the play-off places.