The dbus-daemon in D-Bus 1.2.x through 1.4.x, 1.6.x before 1.6.20, and 1.8.x before 1.8.4, sends an AccessDenied error to the service instead of a client when the client is prohibited from accessing the service, which allows local users to cause a denial of service (initialization failure and exit) or possibly conduct a side-channel attack via a D-Bus message to an inactive service.

The _dbus_header_byteswap function in dbus-marshal-header.c in D-Bus (aka DBus) 1.2.x before 1.2.28, 1.4.x before 1.4.12, and 1.5.x before 1.5.4 does not properly handle a non-native byte order, which allows local users to cause a denial of service (connection loss), obtain potentially sensitive information, or conduct unspecified state-modification attacks via crafted messages.