How to debug a mem leak in a CxxWrap'ed package?

I’m running into an issue with a mem leak in a package that I wrapped using CxxWrap.
I’ve run the offending program with --track-allocation=all, and that pointed to a for loop that retrieves objects from a file, but it didn’t follow the call through the libraries.
I’m a bit puzzled now, because the for loop doesn’t do anything and just returns a pointer to an object. I’m not wrapping the pointer in a custom object, and I don’t own it, so I’m not sure where the allocation comes from. If nothing else, the objects should be gc’ed when they go out of scope, but they just keep piling up.
I would like to track the allocations from my package down to CxxWrap and maybe even to the C++ library if possible. Does anybody have an idea for how to do that?