Security fix

Blackboard Learn 9.1 Q2 2018 

This release contains a security fix to the login page that could interrupt the way third party SSO solutions pass user credentials from a client portal to Blackboard. A one-time nonce value has been added to the login form. This nonce must be passed back to the server with any POST to the login page. Third-party solutions which rely on posting usernames and passwords directly to /webapps/login/ will fail. This is by design. Clients using supported SSO methods including SAML and CAS aren't affected. Clients experiencing difficulty with custom SSO solutions should file a support ticket on Behind the Blackboard.