ADFS?
Fragment of a discussion from Extension talk:LDAP Authentication
SAMLAuth may work. You can likely also use an apache module for this, and then have LDAP auth do auto-auth so that you can pull groups and such too, if you need to.
If you just need authentication, and don't need groups and such, I think there are a few web server authentication plugins for MediaWiki as well, then you can use an Apache module in combination with it.
