Gianluca Gaetano opened the scoring for the home side in Friday night's game after half an hour and Yerry Mina got a second with an almost identical spot kick six minutes later.
Juventus had a first-half goal from Dušan Vlahović disallowed after a video review but the Serbian forward got one back in the 61st minute with a swerving free kick.
Just when it looked like Cagliari would get the win and distance themselves from the relegation zone, Alberto Dossena put the ball into his own net with three minutes left.
Juventus were five points behind second-placed AC Milan and 19 behind champions-elect Inter Milan. Juve hves won only one of their last seven league games.
Cagliari were five points above the relegation zone but still in a dogfight.
Only six points separated Sassuolo in 19th place and Lecce in 13th.
With Salernitana almost certainly going down, two others will join them.
A second-half goal from Luis Alberto gave Lazio a 1-0 win at Genoa and moved the capital club into sixth and within touching distance of a Champions League spot.
The result snapped Genoa's four-game unbeaten run and was another good result for the visitors who had won four of their last five league games.
Lazio was one place and one point ahead of Atalanta, who had two games in hand.
The top five teams in Serie A are guaranteed a place in next year's expanded 36-team Champions League. Sixth spot could be enough if Roma or Atalanta win the Europa League.
Genoa remained in 10th place.
10°C