Authentication is not required in order to trigger this vulnerability.
The flaw exists within Novell's eDirectory Server's NCP implementation which binds, by default, to TCP port 524. While handling a malformed request, the application explicitly trusts a field when translating it to an index into a table of counters. If this index is too large, the application will set a value outside the array and the ndsd process will become unresponsive resulting in an inability to authenticate to that server.
