ASA-2019-00016 – PowerDNS: Lua hooks are not applied in certain configurations

An issue has been found in PowerDNS Recursor where Lua hooks are not properly applied to queries received over TCP in some specific combination of settings, possibly bypassing security policies enforced using Lua. When the recursor is configured to run with more than one thread (threads=X) and to do the distribution of incoming queries to the worker threads itself (pdns-distributes-queries=yes), the Lua script is not properly loaded in the thread handling incoming TCP queries, causing the Lua hooks to not be properly applied.