Updated postfix packages that include a security fix and two other bug fixes are now available for Red Hat Enterprise Linux 4. This update has been rated as having low security impact by the Red Hat Security Response Team
Postfix is a Mail Transport Agent (MTA), supporting LDAP, SMTP AUTH (SASL), and TLS. A flaw was found in the ipv6 patch used with Postfix. When the file /proc/net/if_inet6 is not available and permit_mx_backup is enabled in smtpd_recipient_restrictions, this flaw could allow remote attackers to bypass e-mail restrictions and perform mail relaying by sending mail to an IPv6 hostname. The Common Vulnerabilities and Exposures project (cve.mitre.org) has assigned the name CAN-2005-0337 to this issue. These updated packages also fix the following problems: - wrong permissions on doc directory - segfault when gethostbyname or gethostbyaddr fails All users of postfix should upgrade to these updated packages, which contain patches which resolve these issues.