(RHSA-2011:0422) Moderate: postfix security update

Postfix is a Mail Transport Agent (MTA), supporting LDAP, SMTP AUTH (SASL),
and TLS.

It was discovered that Postfix did not flush the received SMTP commands
buffer after switching to TLS encryption for an SMTP session. A
man-in-the-middle attacker could use this flaw to inject SMTP commands into
a victim’s session during the plain text phase. This would lead to those
commands being processed by Postfix after TLS encryption is enabled,
possibly allowing the attacker to steal the victim’s mail or authentication
credentials. (CVE-2011-0411)

It was discovered that Postfix did not properly check the permissions of
users’ mailbox files. A local attacker able to create files in the mail
spool directory could use this flaw to create mailbox files for other local
users, and be able to read mail delivered to those users. (CVE-2008-2937)

Red Hat would like to thank the CERT/CC for reporting CVE-2011-0411, and
Sebastian Krahmer of the SuSE Security Team for reporting CVE-2008-2937.
The CERT/CC acknowledges Wietse Venema as the original reporter of
CVE-2011-0411.

Users of Postfix are advised to upgrade to these updated packages, which
contain backported patches to resolve these issues. After installing this
update, the postfix service will be restarted automatically.