About This Document
For up to date information on this vulnerability, patches, and other operational information, please see the official vulnerability announcement. This
article is intended to supplement the information in that announcement
and will be updated as needed to further describe the operational impact
of this vulnerability.
Am I vulnerable?
The bug causing this problem was inadvertently introduced in the most recent releases of BIND
9 - so we are confident that this vulnerability only impacts 9.9.3, 9.8.5 and 9.6-ESV-R9 and all of their beta and release candidates (9.9.3b1, 9.9.3b2, 9.9.3rc1, 9.9.3rc2, 9.8.5b1, 9.8.5b2, 9.8.5rc1, 9.8.5rc2, 9.6-ESV-R9b1, 9.6-ESV-R9b2, 9.6-ESV-R9rc1 and 9.6-ESV-R9rc2).
Any server that does recursion for whatever reason could crash as a result of sending queries to and receiving responses from a malformed zone - whether this be accidental or deliberately contrived.
Authoritative-only servers are at less risk, since they only do recursion (i.e. send iterative queries) in very specific and limited circumstances - but they should still be considered vulnerable. For more information on the recursive queries made by authoritative-only servers, see article Why does my authoritative-only nameserver try to query the root nameservers?
If you are hosting authoritative-only DNS services, your risk will most
likely be higher than if you are managing your own authoritative zones
alone. This is because the content of the zones that your customers
upload may cause your servers to make unexpected queries to other
nameservers. DNS Hosting Organizations running Authoritative-only servers on vulnerable versions of BIND are encouraged to upgrade with the same sense of urgency as those running Recursive servers.
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