The default configuration of smbd in Samba before 3.3.11 3.4.x before 3.4.6 and 3.5.x before 3.5.0rc3 when a writable share exists allows remote authenticated users to leverage a directory traversal vulnerability and access arbitrary files by using the symlink command in smbclient to create a symlink containing .. (dot dot) sequences related to the combination of the unix extensions and wide links options.