Ange Postecoglou's side played without spark against the African champions but earned a point when Mark Milligan converted a penalty to cancel out Andre-Frank Zambo Anguissa's first-half finish.
Australia now head to Moscow to play Chile, where they must win and have another result go their way to reach the semi-finals in Russia.
Once again, the Socceroos failed to produce a performance to be proud of, losing the bulk of the battles and the shot count 19-5.
They did at least start more confidently than in their first-up loss to Germany but their ascendancy faded, leaving only Cameroon playing with the urgency that the do-or-die match required.
The African champions were superior both in the air and on the deck.
Impressive youngster Christian Bassogog enjoyed a couple of early sighters, exposing Milos Degenek's lack of pace.
The Socceroo defender was then found wanting for the opener, when Zambo Anguissa beat him to a long ball and dinked an effort over rushing goalkeeper Mat Ryan.
It was no less than Cameroon deserved.
Australia picked up the pace in the second half.
Mat Leckie sent a pair of dangerous balls into the box but they were wasted by Tomi Juric and Tom Rogic.
The match swung again and on 57 minutes, Australia received a life.
Vincent Aboubakar sent a shot both narrowly wide and through Zambo Anguissa's legs just a metre from goal with Ryan beaten.
The move should have put the game on Cameroon's terms but instead, a driving run from Gersbach brought Milligan to the spot.
The impressive 20-year-old was brashly tackled in the box by Ernest Mabouka and the Australian skipper converted.
Postecoglou threw on James Troisi, Tim Cahill and Jackson Irvine looking for a winner.
It wasn't to be, with only a result against the odds against tournament favourites Chile likely to save Postecoglou from criticism of the team's showing in Russia.
Postecoglou rued a "little lapse" for Cameroon's opener, seeing merit in the more composed showing even if they failed to fire up front.
"We worked our way into the game really well and controlled large parts (but) we lacked a little bit of composure in the final third to get some meaningful chances," he said.
"Credit to the players. They worked their hearts out.
"We pressed on and we got the goal I thought we deserved."
Cameroon boss Hugo Broos saw injustice in the result, pointing to the shots-at-goal count.
"The statistics says everything about the game. I think we should have always have won the game," he said.
"On the 90 minutes we were the better team, we had the better chances."
