Yes, audio and camera are there, which means that you also have access to the graphics memory managed by gralloc/hwcomposer too (though surfaceflinger itself is a separate process -- whether mediaserver has access to all such buffers or just ones passed to it from elsewhere is platform-dependent I think), as well as enough of the display driver to spit audio streams out via HDMI, etc...

All that kernel code tends to be complicated and poorly audited, so it would be a plausible hole. But that's not a "sandboxing" problem exactly.