The original fix for CVE-2009-4022 was found to be incomplete. BIND was incorrectly caching certain responses without performing proper DNSSEC validation. CNAME and DNAME records could be cached, without proper DNSSEC validation, when received from processing recursive client queries that requested DNSSEC records but indicated that checking should be disabled. A remote attacker could use this flaw to bypass the DNSSEC validation check and perform a cache poisoning attack if the target BIND server was receiving such client queries.
This issue has been addressed in following products:
Red Hat Enterprise Linux 5
Via RHSA-2010:0062 https://rhn.redhat.com/errata/RHSA-2010-0062.html