Own goal takes Senegal through to final
With 10 minutes gone in extra time, goalkeeper Mouez Hassen pushed a free-kick against the head of Bronn and the ball went backwards into the net.
Tunisia thought they would have a chance to equalise when Idrissa Gueye handled in the box, but the Ethiopian referee rejected their penalty appeals after checking the incident on the VAR monitor.
Both teams missed penalties in regular time with Ferjani Sassi the Tunisian culprit before Henri Saivet failed for the Senegalese.
Senegal will miss star defender Kalidou Koulibaly for the final against Algeria or Nigeria, who meet in Cairo later Sunday, after he was yellow-carded.
It was the second caution of the knockout phase for the Napoli centre-back and triggered an automatic one-match suspension.
Senegal last reached the title decider 17 years ago, when current coach Aliou Cisse captained a team beaten on penalties by Cameroon in Mali.
Senegal took control in the first half and had three good opportunities before half-time to end the deadlock and edge closer to the July 19 final.
Youssouf Sabaly unleashed a curling shot from the edge of the box that beat Mouez but cannoned back into play off the woodwork on 26 minutes.
Then, in a 60-second purple patch, Mbaye Niang and Liverpool star Sadio Mane were unable to convert chances before a small crowd.
Niang swivelled inside the box only to fire well wide and Mane rounded Hassen but his shot from an acute angle finished well off target.
Senegal goalkeeper Alfred Gomis, a virtual spectator in the opening half, reacted quickly early in the second half to push away a Sassi snap shot.
Attackers Niang and Diatta were having little success and came off with Mbaye Diagne and Ismaila Sarr replacing them as an intriguing semi-final entered the final quarter.
The Sassi penalty was weak, allowing Gomis to save comfortably, while Hassen made a brilliant one-hand block to foil a powerfully struck spot-kick by Saivet.