Samba is an open-source implementation of the Server Message Block (SMB) or Common Internet File System (CIFS) protocol, which allows PC-compatible machines to share files, printers, and other information.
The default Samba server configuration enabled both the "wide links" and "unix extensions" options, allowing Samba clients with write access to a share to create symbolic links that point to any location on the file system. Clients connecting with CIFS UNIX extensions disabled could have such links resolved on the server, allowing them to access and possibly overwrite files outside of the share. With this update, "wide links" is set to "no" by default. In addition, the update ensures "wide links" is disabled for shares that have "unix extensions" enabled. (CVE-2010-0926)
Warning: This update may cause files and directories that are only linked to Samba shares using symbolic links to become inaccessible to Samba clients. In deployments where support for CIFS UNIX extensions is not needed (such as when files are exported to Microsoft Windows clients), administrators may prefer to set the "unix extensions" option to "no" to allow the use of symbolic links to access files out of the shared directories. All existing symbolic links in a share should be reviewed before re-enabling "wide links".
These updated samba packages also fix the following bug:
In addition, these updated samba packages provide the following enhancement:
Users are advised to upgrade to these updated samba packages, which correct these issues and add this enhancement. After installing this update, the smb service will be restarted automatically.