RHSA-2011:0423 - Security Advisory

Topic

Updated postfix packages that fix one security issue are now available for
Red Hat Enterprise Linux 6.

The Red Hat Security Response Team has rated this update as having moderate
security impact. A Common Vulnerability Scoring System (CVSS) base score,
which gives a detailed severity rating, is available from the CVE link in
the References section.

Description

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.

Solution

Before applying this update, make sure all previously-released errata
relevant to your system have been applied.

This update is available via the Red Hat Network. Details on how to
use the Red Hat Network to apply this update are available at
https://access.redhat.com/kb/docs/DOC-11259

Affected Products

• Red Hat Enterprise Linux Server 6 x86_64
• Red Hat Enterprise Linux Server 6 i386
• Red Hat Enterprise Linux Workstation 6 x86_64
• Red Hat Enterprise Linux Workstation 6 i386
• Red Hat Enterprise Linux Desktop 6 x86_64
• Red Hat Enterprise Linux Desktop 6 i386
• Red Hat Enterprise Linux for IBM z Systems 6 s390x
• Red Hat Enterprise Linux for Power, big endian 6 ppc64
• Red Hat Enterprise Linux for Scientific Computing 6 x86_64
• Red Hat Enterprise Linux Server from RHUI 6 x86_64
• Red Hat Enterprise Linux Server from RHUI 6 i386
• Red Hat Enterprise Linux Server - Extended Life Cycle Support 6 x86_64
• Red Hat Enterprise Linux Server - Extended Life Cycle Support 6 i386
• Red Hat Enterprise Linux Server - Extended Life Cycle Support (for IBM z Systems) 6 s390x
• Red Hat Enterprise Linux Server - Extended Life Cycle Support Extension 6 x86_64
• Red Hat Enterprise Linux Server - Extended Life Cycle Support Extension 6 i386
• Red Hat Enterprise Linux Server - Extended Life Cycle Support Extension (for IBM z Systems) 6 s390x

Fixes

• BZ - 674814 - CVE-2011-0411 postfix: SMTP commands injection during plaintext to TLS session switch

CVEs

• CVE-2011-0411

References

• https://access.redhat.com/security/updates/classification/#moderate