Shibboleth Embedded Discovery Service V1.2.1 now available
The Shibboleth Project has released a patch for the Embedded Discovery Service that addresses the "open redirector" behavior of the scripts by requiring the deployer to supply an expression to check the return value against. The EDS doesn't rely on SP metadata like the older CDS software, so it didn't have the ability to enforce this automatically.
As mentioned in the release notes , the change was applied in a backward-compatible way, so upgraded systems don't break but can be remediated. New installs will not function out of the box.
The software is available in source form  and the RPMs are building now and will be on the mirrors shortly.