Both mobile and desktop versions of Safari, and Firefox 22 have more strict policies for setting cookies from 3rd-party websites on a page.
CentralAuth's SUL function has used a set of images that contact the other websites in $wgCentralAuthAutoLoginWikis, which set a 3rd-party cookie for that site in case the user later visited.
The SUL mechanism needs to be updated to accommodate this. Planning and design for the rework are documented at http://www.mediawiki.org/wiki/Auth_systems/SUL2
Version: master
Severity: normal