JBoss SSO is not maintained across two virtual servers

Issue

• We set up multiple virtual-servers in our web subsystem, one for each application. Each is set up for SSO like below, but we see that SSO is not properly maintained across the applications. After logging out of one application, the user is still logged in on the other application(s).

            <virtual-server name="vhost1" enable-welcome-root="false">
                <alias name="vhost2.site.com"/>
                <sso cache-container="web" cache-name="sso" domain="site.com"/>
            </virtual-server>
            <virtual-server name="vhost2" enable-welcome-root="false">
                <alias name="vhost2.site.com"/>
                <sso cache-container="web" cache-name="sso" domain="site.com"/>
            </virtual-server>