php-cas vulnerability

Filip Hejsek discovered that phpCAS was using HTTP headers to determine
the service URL used to validate tickets. A remote attacker could
possibly use this issue to gain access to a victim's account on a
vulnerable CASified service.

This security update introduces an incompatible API change. After applying
this update, third party applications need to be modified to pass in an
additional service base URL argument when constructing the client class.

For more information please refer to the section
"Upgrading 1.5.0 -> 1.6.0" of the phpCAS upgrading document:

https://github.com/apereo/phpCAS/blob/master/docs/Upgrading