The RPC Code Generator in Samba is prone to an overflow condition. The network data representation fails to properly sanitize user-supplied input resulting in a heap-based buffer overflow. With multiple specially crafted requests, a remote attacker can potentially execute arbitrary code.
Upgrade to version 3.6.4, 3.5.14, or 3.4.16 or higher, as they have as been reported to fix this vulnerability. In addition, the vendor has released a patch for some older versions.