Experts say there also is an exploit for the vulnerability that is already circulating widely online. The BIND vulnerability is in version 9 of the software, and the Internet Systems Consortium, which maintains BIND, said there is no workaround for the problem. Access controls will not provide an effective workaround, the ISC says. The ISC has released updated versions of BIND software that contain a fix for the issue: versions 9.4.3-P3, 9.5.1-P1 and 9.6.1.
Source: https://threatpost.com/exploit-circulating-critical-new-bind-dns-flaw-072909/73012/