Debian Security Advisory 1628-1 – Brian Dowling discovered that the PowerDNS authoritative name server does not respond to DNS queries which contain certain characters, increasing the risk of successful DNS spoofing. This update changes PowerDNS to respond with SERVFAIL responses instead.
You can download this advisory from the following link: https://packetstormsecurity.com/files/download/69001/dsa-1628-1.txt
Source: https://packetstormsecurity.com/files/69001/Debian-Linux-Security-Advisory-1628-1.html