Authorization Bypass in Spring Security

When using Spring Security’s CAS Proxy ticket authentication a malicious CAS Service could trick another CAS Service into authenticating a proxy ticket that was not associated. This is due to the fact that the proxy ticket authentication uses the information from the HttpServletRequest which is populated based upon untrusted information within the HTTP request.

This means if there are access control restrictions on which CAS services can authenticate to one another, those restrictions can be bypassed.

If users are not using CAS Proxy tickets and not basing access control decisions based upon the CAS Service, then there is no impact to users.

Mitigation

Users of affected versions should apply the following mitigation:

• Users of 3.2x should upgrade to 3.2.5 or later
• Users of 3.1.x should upgrade to 3.1.7 or later

Credit

This issue was identified by David Ohsie and brought to our attention by the CAS Development team.