DOS vulnerability in BIND

Sorry for changing the title, but the page title didn't really convey how serious this is. There is an additional post on the ISC site which says:

"Many of our bugs are limited in scope or affect only users having a particular set of configuration choices. CVE-2015-5477 does not fall into that category. Almost all unpatched BIND servers are potentially vulnerable... The practical effect of this is that this bug is difficult to defend against (except by patching, which is completely effective) and will not be particularly difficult to reverse-engineer."

https://www.isc.org/blogs/about-cve-2015-5477-an-error-in-ha...