wu-ftpd 2.6.2 and earlier, with the restricted-gid option enabled, allows local users to bypass access restrictions by changing the permissions to prevent access to their home directory, which causes wu-ftpd to use the root directory instead.
https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A648
https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A1637
https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A1636
https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A1147
https://exchange.xforce.ibmcloud.com/vulnerabilities/15423
http://www.securityfocus.com/bid/9832
http://www.redhat.com/support/errata/RHSA-2004-096.html
http://www.frsirt.com/english/advisories/2006/1867
http://www.debian.org/security/2004/dsa-457
http://sunsolve.sun.com/search/document.do?assetkey=1-26-102356-1
http://secunia.com/advisories/20168