The pcs packages provide a command-line tool and a web UI to configure and manage the Pacemaker and Corosync tools. It was found that the pcs daemon did not sign cookies containing session data that were sent to clients connecting via the pcsd web UI. A remote attacker could use this flaw to forge cookies and bypass authorization checks, possibly gaining elevated privileges in the pcsd web UI. This issue was discovered by Tomas Jelinek of Red Hat. This update also fixes the following bug: * Previously, the Corosync tool allowed the two_node option and the auto_tie_breaker option to exist in the corosync.conf file at the same time. As a consequence, if both options were included, auto_tie_breaker was silently ignored and the two_node fence race decided which node would survive in the event of a communication break. With this update, the pcs daemon has been fixed so that it does not produce corosync.conf files with both two_node and auto_tie_breaker included. In addition, if both two_node and auto_tie_breaker are detected in corosync.conf, Corosync issues a message at start-up and disables two_node mode. As a result, auto_tie_breaker effectively overrides two_node mode if both options are specified. All pcs users are advised to upgrade to these updated packages, which contain backported patches to correct these issues. After installing the updated packages, the pcsd daemon will be restarted automatically.