(RHSA-2011:0423) 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)

Red Hat would like to thank the CERT/CC for reporting CVE-2011-0411. The
CERT/CC acknowledges Wietse Venema as the original reporter.

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