Well, the license (CC-By-SA) requires that "The credit required by this Section 4(c) may be implemented in any reasonable manner;". So it doesn't need to be in the footer of the map, when there is no footer at all ("at least as prominent as the credits for the other contributing authors"), but I think the EULA/about not reasonable.
But other people might disagree. There are even people that think the whole license is invalid and that it can be used as Public Domain, because the license is for creative work and not meant to be used for databases. This is the major reason OSM is changing to a different license right now (ODbL).
It depends on what you want to do with the image: https://developer.mozilla.org/en-US/docs/Web/HTML/CORS_enabl...