CVE 2012-1193
The resolver in PowerDNS Recursor (aka pdns_recursor) 3.3 overwrites cached server names and TTL values in NS records during the processing of a response to an A record query, which allows remote attackers to trigger continued resolvability of revoked domain names via a "ghost domain names" attack.
See the
CVE page on Mitre.org
for more details.