I release many of my photos under one or more Creative Commons licenses. One of them was recently uploaded to Wikimedia Commons, and I was approached by a moderator there with an inquiry whether I had a model release (in not so few words) from the model allowing republication of the photo.
As I understand it, my licensing of my rights under copyright (which I hold solely) has no interaction with the model's rights (which she holds, and may have licensed to me under some terms). I can give you my permission to use the photo, in which case you can use it in some fashion iff you don't need (under your local laws) her permission to use it in that way, otherwise you need to also get her permission (which you might get through me, if she has released those rights to me).
Can anyone further or more accurately explain how these two interplay?