The MITRE CVE dictionary describes this issue as:
ftpd.c in (1) wu-ftpd 2.4.2 and (2) ftpd in HP HP-UX B.11.11 assigns uid 0 to the FTP client in certain operating-system misconfigurations in which PAM authentication can succeed even though no passwd entry is available for a user, which allows remote attackers to gain privileges, as demonstrated by a login attempt for an LDAP account when nsswitch.conf does not specify LDAP for passwd information.
Find out more about CVE-2008-1668 from the
MITRE CVE dictionary dictionary and
NIST NVD.
Statement
Not vulnerable. This flaw does not affect teh version of wu-ftpd as shipped in Red Hat Enterprise Linux 2.1.