Coman prodded the ball in on the a ways put up within the final minute of ordinary time to cancel out Junior Adamu's first-1/2 opener and store Bayern from a first away defeat within the competition for the reason that 2017.
Bayern arrived in Austria trying to get better from their shock defeat to Bundesliga minnows Bochum on Saturday, however there were early symptoms of the equal defensive wobbles which had plagued them at the weekend.
A mistake from Niklas Suele spread out a risk for Brenden Aaronson after just a few minutes, as Salzburg snapped at the heels of the Bayern lower back line.
The visitors additionally had chances at the alternative end, but persisted to look prone and Salzburg deserved their lead on 21 minutes.
A soaring long ball from Mohamed Camara opened Bayern up on the counter-assault, and Adamu curled the ball in with an stylish first-time finish.
Adamu had come on as an early alternative for the injured Noah Okafor, and he and his fellow forwards persisted to unsettle the Bayern defence earlier than the break.
The hosts had a penalty enchantment waved away simply earlier than half-time, earlier than sitting returned and absorbing pressure in the 2nd half.
But no matter dominating ownership and jogging Salzburg's full-backs ragged, Bayern toiled of their search for an equaliser.
As the stress installed closer to the cease of the sport, Salzburg keeper Philipp Koehn denied Coman with a reflex keep and neutralised a pointy counter-assault by means of snatching the ball from the feet of Leroy Sane.
