Single Logout in Shibboleth IdP Important notes on third party cookies In some browsers, the IFrame-driven front-channel logout doesn't work due to the browser blocking third party cookies . Every cookie which is sent to a foreign domain via img, iframe, script, etc. tags is considered to be third party, so the session cookie of the SP software in a foreign domain is third party cookie when it is sent in an IFrame. By blocking these cookies, the SP doesn't receive the session cookie and thus it could stop processing the logout request at this point. Additional links: Shibboleth-dev thread on the issue How to disable third party cookies in firefox Additional explanation in Mozilla Bugzilla Same origin policy for cookies Further information on third party cookie handling "Although any third-party cookie restrictions are not a sufficient method to prevent cross-domain user tracking, they prove to be rather efficient in disrupting or impacting the security of some legitimate web site features, most notably certain web gadgets and authentication mechanisms." Why service providers might need the session cookie Most of the services do not need the session cookie itself, they only need the NameIdentifier, which is carried by the logout request, so back-channel logout requests are enough for them. But there might be service providers which do not implement back-channel bindings (eg. SimpleSAMLphp), or need front-channel application notification. Why not fully back-channel? SAML profiles specification (section 4.4.3.1) clearly states that front-channel should be preferred when sending the logoutrequest to the session authority (IdP). If the user interface is generated by the IdP, it could inform the user about the whole logout process, and each SP response. If the SP would use back-channel logoutrequest, the IdP's response would only contain minimal information (ie. success or failure), and this is not desirable. Also, the IdP would need to execute back-channel requests in parallel and synchronize them with the originating request, so this would make the processing code much more complex. Technical solution Our proposal is to prefer back-channel endpoints at the service provider side, unless your application needs to be notified via front-channel. For example, if your application behind your SP needs the session cookie with the notification, use only front-channel bindings in the SP metadata, otherwise use only back-channel binding in the SP metadata. By these mutually exclusive endpoint sets, the SP can clearly advise the IdP which binding it should use when contanting this SP. Thus on the IdP side, both implementations need to be available. Non-technical solution Another option would be to add a new requirement for your end users. You can claim that banning third-party cookies is unsupported (because it breaks SLO), just like disabling all cookies (which breaks SSO). Convincing your users (and the Shibboleth developers to accept this solution) might be dubious, though. Features Implements SAML2 Single Logout profile If initiated by an SP, user must confirm the single logout process: one can choose to logout only from the initiating SP and the IdP. Highly customizable front-channel logout interface which leverages javascript and asynchronous operations in order to provide a clean, simple UI. UI is usable with javascript disabled. Supports localized SP name lookup via Organization elements in SAML metadata . Fallback to back-channel logout if front-channel is not supported by the SP. Supports Shibboleth SSO sessions (if the SP initiates sessions using Shibboleth1.3 protocol, but supports SAML2 logout). Supports full back-channel operation. Supports IdP-initiated Single Logout. UI customization The UI is located in two JSP files: sloQuestion.jsp the user chooses whether she wants to logout from all service providers or just from the provider where she came from. sloController.jsp is the logout UI where every session participant and their corresponding logout status is shown. At the end of the logout process, the user is notified if the single logout was completed. How it works SLOServlet The heart of the logout process is the SLOServlet . This servlet is responsible for these actions: rendering the logout question and controller page initiating front-channel or back-channel logout to one SP ( SLOServlet?action&entityID=... ) returning the logout status as a JSON string ( SLOServlet?status ) With javascript The controller renders a page where an iframe is placed for every active session participant. This iframe calls the SLOServlet?action&entityID=... URL where the logout request is issued for the given session participant. If the request is front-channel, the iframe will make a front-channel SAML message exchange with the peer (using HTTP-Redirect or POST bindings). The status of the single logout process is queried via asynchronous requests. The status response from SLOServlet is a JSON array. This JSON array contains one object with the entityID and logoutStatus properties for each session participant. The logout status can be one of the followings: LOGGED_IN : logout is not initiated for this participant yet. LOGOUT_ATTEMPTED : logout was initiated. LOGOUT_FAILED : logout failed. LOGOUT_UNSUPPORTED : SAML2 logout is not supported by the participant (the metadata does not contain the necessary endpoints). LOGOUT_TIMED_OUT : timed out waiting for a response. LOGOUT_SUCCEEDED : logout was successful. Status queries are issued using exponential backoff timing, until the timeout is reached. Please see the sloController.jsp for the exact timing used. Without javascript Controller renders an HTML page with