A flaw was found in the way samba implemented an RPC endpoint emulating the Windows registry service API. An unprivileged attacker could use this flaw to create a new registry hive file anywhere they have unix permissions which could lead to creation of a new file in the Samba share.
Either turn off SMB1 by setting the global parameter:
'min protocol = SMB2'
or if SMB1 is required turn off unix extensions by setting the global parameter:
'unix extensions = no'
in the smb.conf file.