D-Bus is a system for sending messages between applications. It is used for the system-wide message bus service and as a per-user-login-session messaging facility. A denial of service flaw was discovered in the system for sending messages between applications. A local user could send a message with an excessive number of nested variants to the system-wide message bus, causing the message bus to abort. All users are advised to upgrade to these updated packages, which contain a backported patch to correct this issue. For the update to take effect, all running instances of dbus-daemon and all running applications using the libdbus library must be restarted, or the system rebooted.