smbd in Samba 3.3.11, 3.4.6, and 3.5.0, when libcap support is enabled, runs with the CAP_DAC_OVERRIDE capability, which allows remote authenticated users to bypass intended file permissions via standard filesystem operations with any client.
https://bugzilla.samba.org/show_bug.cgi?id=7222
http://www.samba.org/samba/security/CVE-2010-0728
http://www.samba.org/samba/history/samba-3.5.1.html
http://www.samba.org/samba/history/samba-3.4.7.html
http://www.samba.org/samba/history/samba-3.3.12.html
http://lists.samba.org/archive/samba-announce/2010/000211.html