(RHSA-2015:2455) Low: unbound security and bug fix update

The unbound packages provide a validating, recursive, and caching DNS or
DNSSEC resolver.

A denial of service flaw was found in unbound that an attacker could use to
trick the unbound resolver into following an endless loop of delegations,
consuming an excessive amount of resources. (CVE-2014-8602)

This update also fixes the following bugs:

• Prior to this update, there was a mistake in the time configuration in
  the cron job invoking unbound-anchor to update the root zone key.
  Consequently, unbound-anchor was invoked once a month instead of every day,
  thus not complying with RFC 5011. The cron job has been replaced with a
  systemd timer unit that is invoked on a daily basis. Now, the root zone key
  validity is checked daily at a random time within a 24-hour window, and
  compliance with RFC 5011 is ensured. (BZ#1180267)

• Previously, the unbound packages were installing their configuration file
  for the systemd-tmpfiles utility into the /etc/tmpfiles.d/ directory. As a
  consequence, changes to unbound made by the administrator in
  /etc/tmpfiles.d/ could be overwritten on package reinstallation or update.
  To fix this bug, unbound has been amended to install the configuration file
  into the /usr/lib/tmpfiles.d/ directory. As a result, the system
  administrator’s configuration in /etc/tmpfiles.d/ is preserved, including
  any changes, on package reinstallation or update. (BZ#1180995)

• The unbound server default configuration included validation of DNS
  records using the DNSSEC Look-aside Validation (DLV) registry. The Internet
  Systems Consortium (ISC) plans to deprecate the DLV registry service as no
  longer needed, and unbound could execute unnecessary steps. Therefore, the
  use of the DLV registry has been removed from the unbound server default
  configuration. Now, unbound does not try to perform DNS records validation
  using the DLV registry. (BZ#1223339)

All unbound users are advised to upgrade to these updated packages, which
contain backported patches to correct these issues.