It is important to first follow the steps in the Release Notes for v2.6.0.

The SSP development team is not aware of any SSP deployments integrated with CAS, but this release includes two security-related patch sets specifically targeted at CAS integrations:

• SSP-2721 - Scrubs certain CAS-specific request parameters. The changes and effects are detailed in the uPortal project.  No work should be required to enable the patch, but you may want to review that document to better understand the CAS-related configuration changes included in this release.
• SSP-2724 - Works around what amounts to a CAS-specific session hijacking vulnerability. The changes and effects are detailed in the uPortal project and the <platform-src>/uportal-war/src/main/resources/properties/security.properties file includes greatly expanded comments describing recommended configuration changes. You will likely want to review the email thread and changes to that file whether or not you use CAS. The new defaults may interfere with your existing authentication provider integrations, especially AD/LDAP. SSP-specific details below.
• SSP-3130 - Upgrade Apache Commons Security Issue. A patch was added for Apache security into 2.8 and rel-2-7-patches. None changes were made to 2.6.