It looked as though Jon Brady had ended United's worrying month-long wait with a 71st minute header from Courtney Pitt's well-flighted corner.
Usually the provider of crosses for the forwards the winger turned goalscorer when he cleverly lost his marker at the set piece and nodded the ball down between goalkeeper Scott Bevan and the far post.
It took Cambridge into a well-deserved lead against a toothless Kidderminster side and provided encouragement for the list of candidates for the vacant manager's job.
Apart from a slumbering spell late in the first half Cambridge always looked the more likely scorers than the hapless Harriers.
They carved out half a dozen solid scoring chances, and even claimed they'd got a goal in the 10th minute when new skipper Rob Wolleaston hammered in a shot which struck the crossbar and bounced down into the goalmouth.
As the ball bounced back into the penalty area Wolleaston raised his hands in celebration at scoring, but referee Guy Stretton angered the fans by waving play on.
There was worst to come, however, for the Abbey Stadium supporters who were celebrating a victory in the dying moments.
Suddenly Russell broke clear, found the defence in disarray as he ran into the box and hit a shot which struck the ground and bounced over goalkeeper Paul Crichton.
It preserved the Harriers' unbeaten record at Cambridge and ended eight hours and 23 minutes without a goal for his team.
It was the visitors' first shot on target of the night but amazingly, they went close to snatching victory when Bob Taylor headed over the crossbar in stoppage time and Russell had a shot blocked from a good position.
Such a result, though, would have been rough justice for a Cambridge team who showed a huge improvement from Saturday's scrappy 1-1 draw at Forest Green.
Inspired by Wolleaston and winger Pitt who ran rings around the Harriers defence, they carved out enough opportunities to have made Russell's late equaliser an irrelevance.
Just a couple of minutes after Wolleaston's shot struck the crossbar, a pinpoint centre from Pitt gave Brady the chance of a fierce volley which looked on his way into the net until it was blocked by Jonny Harkness.
After a spell of stalemate in which Kidderminster had more possession but were of no real threat, Wolleaston went close again in the 38th minute, turning superbly at the angle of the box and forcing an excellent save from goalkeeper Bevan.
Cambridge looked more lively right from the start of the second period, worrying the visitors' defence on the hour when Marcus Richardson turned, despite being closely marked, to aim a shot a foot wide of the post.
Kidderminster boss, Mark Yates, showed what he thought of his strikers by hauling both Luke Reynolds and Iyseden Christie off in the 62nd minute and replacing them with Andy White and Taylor.
But it made little difference and it was no surprise nine minutes later when United's pressure forced the corner which led to Brady's goal.
A minute later Brady had the chance to seal victory when he hammered in a ground shot which was scrambled away at the last minute by a defender.
It looked nothing more than desperation when Yates threw on Russell on as an extra forward with ten minutes to go and Cambridge appeared to be cruising to the victory to lift them away from the foot of the table.
However, a defence, solid and well organised up to then, lost concentration for the moment which allowed Russell to grab a goal and a point his team could not have been hoping for as the game entered the last few minutes.