16 Malibu Limited Trunk Opening On Own (not bc of fob)
 

My trunk is randomly opening on it's own. This doesn't seem to be because of the common key fob problems others have posted on either. The button on the back of my trunk is not working also. The only way my trunk will pop (when prompted) is if I use my key fob. I have noticed my trunk will pop on it's own a few different times. Most commonly is when I unlock my car then the trunk opens. Also I've had it happen multiple times when car was already unlocked I'd walk up and open say the rear passenger door or driver door and the trunk suddenly pops. Many times I've walked outside to my trunk open realizing I must have forgotten to lock car. My keys are always hanging on a wall hook so I know I'm not hitting my key fob by accident. I live off a busy road in the city and my only option is to park where my trunk is right at the sidewalk. My boyfriend just lost a valuable purchase out of the back of my trunk not knowing my car was having this problem. Any ideas besides having to crawl through the backseat access every time would be appreciated.

I dont have a solution for you. My trunk has opened a few times, but that was becuase the fob was in my pants pockets , along the change, ect. If I keep it in my jacket pocket it never opens up accidentally.

Suggest you make appointment with a GM dealership and have their service department diagnose this problem.
They certainly can solve this issue and cover it under warranty.
Keep us posted !