Thomas Muller and Andre Schurrle looked to have put Joachim Low's side on course for victory when they struck to swiftly overturn Samuel Eto'o's 62nd-minute opener in Monchengladbach.
However, Eric Maxim Choupo-Moting equalised 12 minutes from time to send the visitors away with a positive result after an equally positive performance, which raised more questions about the strength of the Germany defence.
Germany face Armenia in their final pre-World Cup friendly on Friday before flying out to Brazil next Saturday, and Low must decide on Monday which 23 players he will be taking with him on that trip.
Low gave Erik Durm his international debut at left-back in a defensive like which would otherwise be a good bet for Germany's Group G opener against Portugal.
With Sami Khedira back from injury, and Thomas Muller, Mesut Ozil and Marco Reus playing behind Mario Gotze, Low's team was hardly experimental as he appeared keen on seeing only the players he intends to send into action in South America.
And the early signs will have encouraged him.
Gotze went close in the 11th minute with a shot which Charles Itandje managed to push onto the post as Germany's attacking style caused Cameroon problems.
Their reaction was to get physical and interrupt the Germans' flow with fouls - a tactic which worked, earning them a foothold back in the game while frustrating their hosts.
Volker Finke's men nearly took the lead too before half-time when Moukandjo was sent through by Eto'o, but Roman Weidenfeller came out on top of their duel with a reflex stop.
Cameroon showed what had become clear in previous international friendlies - that Germany are susceptible when they are attacked. After just over an hour, the visitors took the lead.
Eto'o's shot was saved well by Weidenfeller, but Mainz forward Choupo-Moting picked up the rebound and set up Eto'o to score at the second attempt.
Germany's answer was not long in coming, though, with Jerome Boateng's cross headed in by Muller before the first jeers could be heard inside the Borussia Park Stadion.
Five minutes later, Chelsea midfielder Schurrle tucked the ball into an open goal after good work from fellow substitute, Arsenal winger Lukas Podolski.
It was Cameroon's turn to respond, and they did so emphatically, levelling in the 78th minute when Choupo-Moting showed the kind of skills which earned Mainz a place in the Europa League next season to beat Weidenfeller.
Durm's debut ended soon after, and he now faces an anxious wait to find out if he did enough to convince Low to take him to Brazil.
The Germany coach has to submit his final squad list on Monday, and must find three names to strike from the 26 players he has been assessing in training over the past fortnight.