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.
https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A5971
https://exchange.xforce.ibmcloud.com/vulnerabilities/44414
http://www.vupen.com/english/advisories/2008/2364
http://www.securitytracker.com/id?1020682
http://www.securityfocus.com/bid/30666
http://www.openwall.com/lists/oss-security/2008/08/20/4
http://secunia.com/advisories/31471
http://h20000.www2.hp.com/bizsupport/TechSupport/Document.jsp?objectID=c01525562