The remote Samba server is affected by multiple buffer overflow vulnerabilities.
According to its banner, the version of Samba 3.x running on the remote host is earlier than 3.6.4 / 3.5.14 / 3.4.16. It is, therefore, affected by multiple heap-based buffer overflow vulnerabilities. An error in the DCE/RPC IDL (PIDL) compiler causes the RPC handling code it generates to contain multiple heap-based buffer overflow vulnerabilities. This generated code can allow a remote, unauthenticated attacker to use malicious RPC calls to crash the application and possibly execute arbitrary code as the root user. Note that Nessus has not actually tried to exploit this issue or otherwise determine if one of the associated patches has been applied.
Either install the appropriate patch referenced in the project's advisory or upgrade to 3.6.4 / 3.5.14 / 3.4.16 or later.