RHSA-2013:0520 - Security Advisory

Topic

Updated dovecot packages that fix three security issues and one bug are now
available for Red Hat Enterprise Linux 6.

The Red Hat Security Response Team has rated this update as having low
security impact. Common Vulnerability Scoring System (CVSS) base scores,
which give detailed severity ratings, are available for each vulnerability
from the CVE links in the References section.

Description

Dovecot is an IMAP server, written with security primarily in mind, for
Linux and other UNIX-like systems. It also contains a small POP3 server. It
supports mail in either of maildir or mbox formats. The SQL drivers and
authentication plug-ins are provided as sub-packages.

Two flaws were found in the way some settings were enforced by the
script-login functionality of Dovecot. A remote, authenticated user could
use these flaws to bypass intended access restrictions or conduct a
directory traversal attack by leveraging login scripts. (CVE-2011-2166,
CVE-2011-2167)

A flaw was found in the way Dovecot performed remote server identity
verification, when it was configured to proxy IMAP and POP3 connections to
remote hosts using TLS/SSL protocols. A remote attacker could use this flaw
to conduct man-in-the-middle attacks using an X.509 certificate issued by
a trusted Certificate Authority (for a different name). (CVE-2011-4318)

This update also fixes the following bug:

• When a new user first accessed their IMAP inbox, Dovecot was, under some

circumstances, unable to change the group ownership of the inbox directory
in the user's Maildir location to match that of the user's mail spool
(/var/mail/$USER). This correctly generated an "Internal error occurred"
message. However, with a subsequent attempt to access the inbox, Dovecot
saw that the directory already existed and proceeded with its operation,
leaving the directory with incorrectly set permissions. This update
corrects the underlying permissions setting error. When a new user now
accesses their inbox for the first time, and it is not possible to set
group ownership, Dovecot removes the created directory and generates an
error message instead of keeping the directory with incorrect group
ownership. (BZ#697620)

Users of dovecot are advised to upgrade to these updated packages, which
contain backported patches to correct these issues. After installing the
updated packages, the dovecot 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/knowledge/articles/11258

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 for IBM z Systems 6 s390x
• Red Hat Enterprise Linux for Power, big endian 6 ppc64
• 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

Fixes

• BZ - 709095 - CVE-2011-2166 dovecot: authenticated remote bypass of intended access restrictions
• BZ - 709097 - CVE-2011-2167 dovecot: directory traversal due to not obeying chroot directive
• BZ - 754980 - CVE-2011-4318 dovecot: proxy destination host name not checked against SSL certificate name

CVEs

• CVE-2011-2166
• CVE-2011-2167
• CVE-2011-4318

References

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