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.
A denial of service flaw was found in the LDAP server provided by the AD DC in the Samba process daemon. A remote attacker could exploit this flaw by sending a specially crafted packet, which could cause the server to consume an excessive amount of memory and crash. (CVE-2015-7540)
Multiple buffer over-read flaws were found in the way Samba handled malformed inputs in certain encodings. An authenticated, remote attacker could possibly use these flaws to disclose portions of the server memory. (CVE-2015-5330)
A man-in-the-middle vulnerability was found in the way "connection signing" was implemented by Samba. A remote attacker could use this flaw to downgrade an existing Samba client connection and force the use of plain text. (CVE-2015-5296)
A missing access control flaw was found in Samba. A remote, authenticated attacker could use this flaw to view the current snapshot on a Samba share, despite not having DIRECTORY_LIST access rights. (CVE-2015-5299)
An access flaw was found in the way Samba verified symbolic links when creating new files on a Samba share. A remote attacker could exploit this flaw to gain access to files outside of Samba's share path. (CVE-2015-5252)
Red Hat would like to thank the Samba project for reporting these issues. Upstream acknowledges Stefan Metzmacher of the Samba Team and Sernet.de as the original reporters of CVE-2015-5296, firstname.lastname@example.org as the original reporter of CVE-2015-5299, Jan "Yenya" Kasprzak and the Computer Systems Unit team at Faculty of Informatics, Masaryk University as the original reporters of CVE-2015-5252 flaws, and Douglas Bagnall as the original reporter of CVE-2015-5330.
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.