It was reported [1] that when the BIND authoritative name server daemon (named) processed a successful IXFR transfer or a dynamic update, there was a small period of time during which the IXFR/update, along with a query, could cause the server to stop processing all requests. A higher update and/or query rate would increase the probability of the deadlock occurring. This flaw only affects BIND 9.7.1 and 9.7.2; upstream has released 9.7.3 to correct this flaw. Upstream also documents that using the "-n1" option to cause named to use only one worker thread would mitigate this problem. [1] https://www.isc.org/software/bind/advisories/cve-2011-0414
Upstream verified to me that this was introduced in 9.7.1, so bind in RHEL6 is not vulnerable. The fix is also noted as: Corrected a defect where a combination of dynamic updates and zone transfers incorrectly locked the in-memory zone database, causing named to freeze. [RT #22614] in http://ftp.isc.org/isc/bind9/9.7.3/RELEASE-NOTES-BIND-9.7.3.html 9.7.3 is currently in Fedora 13 and 14 testing repositories.
Statement: Not vulnerable. This issue did not affect the versions of bind as shipped with Red Hat Enterprise Linux 4, 5, or 6.