The Berkeley Internet Name Domain is an implementation of the Domain Name System protocols. BIND includes a DNS server ; a resolver library ; and tools for verifying that the DNS server is operating correctly. A flaw was found in the BIND DNSSEC NSEC/NSEC3 validation code. If BIND was running as a DNSSEC-validating resolver, it could incorrectly cache NXDOMAIN responses, as if they were valid, for records proven by NSEC or NSEC3 to exist. A remote attacker could use this flaw to cause a BIND server to return the bogus, cached NXDOMAIN responses for valid records and prevent users from retrieving those records . 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. All BIND users are advised to upgrade to these updated packages, which contain a backported patch to resolve these issues. After installing the update, the BIND daemon will be restarted automatically.