Summary: Another system on the network could take root privileges on a vulnerable Samba client or server.
The latest in a recent series of updates to the Samba file system software fixes a critical vulnerability that could allow an attacker on the local network to take control of a host running a vulnerable version of the Samba nmbd NetBIOS name services daemon.
Samba is an open source implementation of the SMB/CIFS network file sharing protocol. SMB/CIFS is most famous as the protocol used in file sharing over Microsoft Windows networks, and Samba exists largely for non-Windows interoperability with those networks. nmbd is a server component of it which responds to NetBIOS requests over IP networks, associating NetBIOS names and IP addresses.
Microsoft® Windows Insider MVP - Windows Security