Josh Scott had 20 points and 10 rebounds to lead Colorado (16-6, 5-4 Pac-12), which averted losing a third straight. Askia Booker added 18 points for the Buffaloes, who have beaten the Utes eight of the last nine times in Boulder.
It was another tough setback for Utah (14-7, 3-6). The Utes have lost their seven games this season by a combined total of 26 points.
Delon Wright and Brandon Taylor each scored 17 to lead the Utes, who remain winless in five conference road games this season.
Down 47-35 after Taylor's layup with 16:52 left, Colorado got back in the game on the strength of a 14-2 flurry, punctuated by back to back 3-pointers by Talton that pulled the Buffaloes into a 49-all tie with 11:13 remaining.
The teams battled down the stretch, keeping it close the rest of the way.
With 2:14 left, Scott snapped a 60-all tie by making a pair of free throws but Jeremy Olsen quickly retied it with a driving layup.
After a Utah turnover, Wesley Gordon was fouled on an inside shot and made one of two free throws as Colorado regained the lead. Utah again turned it over on its ensuing possession and Josh Scott collared the loose ball, drawing a foul and making both free throws for a 65-62 Colorado lead with 19.2 seconds left.
But Taylor connected on a 3-pointer from the top of the key with six seconds remaining in regulation, tying it up and forcing overtime after Askia Booker missed a long jumper as time expired in regulation.
Talton hit a 3-pointer to start overtime, giving Colorado a lead it would not relinquish as the Buffaloes outscored the Utes 14-10 in the extra session.
Colorado was leading 26-19 when Utah put together a 14-0 run, fueled by Taylor's third 3-pointer of the game and successive fastbreak layups by Ahmad Fields and Delon Wright that each followed Colorado turnovers.
Josh Scott's layup broke up Utah's run, but the Utes outscored the Buffaloes 6-3 over the last two minutes of the opening period to take a 37-31 halftime lead.