Updated dovecot 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 base score, which gives a detailed severity rating, is available from the CVE link in the References section. Description Dovecot is an IMAP server for Linux, UNIX, and similar operating systems, primarily written with security in mind. A denial of service flaw was found in the way Dovecot handled NULL characters in certain header names. A mail message with specially-crafted headers could cause the Dovecot child process handling the target user"s connection to crash, blocking them from downloading the message successfully and possibly leading to the corruption of their mailbox. Users of dovecot are advised to upgrade to these updated packages, which contain a backported patch to resolve this issue. After installing the updated packages, the dovecot service will be restarted automatically.