Samba is an open-source implementation of the Server Message Block or Common Internet File System protocol, which allows PC-compatible machines to share files, printers, and other information. A heap-based buffer overflow flaw was found in Samba"s NetBIOS message block daemon . An attacker on the local network could use this flaw to send specially crafted packets that, when processed by nmbd, could possibly lead to arbitrary code execution with root privileges. This update also fixes the following bug: * Prior to this update, Samba incorrectly used the O_TRUNC flag when using the open system call to access the contents of a file that was already opened by a different process, causing the file"s previous contents to be removed. With this update, the O_TRUNC flag is no longer used in the above scenario, and file corruption no longer occurs. All Samba users are advised to upgrade to these updated packages, which contain backported patches to correct these issues. After installing this update, the smb service will be restarted automatically.