Moderate: cyrus-imapd security update

Updated cyrus-imapd packages that fix one security issue are now available
for Red Hat Enterprise Linux 4, 5, and 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.

The cyrus-imapd packages contain a high-performance mail server with IMAP,
POP3, NNTP, and Sieve support.

It was discovered that cyrus-imapd did not flush the received commands
buffer after switching to TLS encryption for IMAP, LMTP, NNTP, and POP3
sessions. A man-in-the-middle attacker could use this flaw to inject
protocol commands into a victim's TLS session initialization messages. This
could lead to those commands being processed by cyrus-imapd, potentially
allowing the attacker to steal the victim's mail or authentication
credentials. (CVE-2011-1926)

Users of cyrus-imapd are advised to upgrade to these updated packages,
which contain a backported patch to correct this issue. After installing
the update, cyrus-imapd will be restarted automatically.

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

705288 - CVE-2011-1926 cyrus-imapd: STARTTLS plaintext command injection

https://www.redhat.com/security/data/cve/CVE-2011-1926.html
https://access.redhat.com/security/updates/classification/#moderate