A specially crafted DNS query may cause Unbound to respond with an empty UDP packet which triggers an assertion failure and stops the daemon.
NLnetLabs advisory states:
"Certain types of DNS queries may cause Unbound to respond with a DNS error message. The code generating this error message contains an error whereby Unbound constructs an empty UDP message. That empty UDP message triggers an assertion failsafe in the part of Unbound that is invoked when the interface-automatic option is set. In the case that the interface-automatic option was not set or assertion failsafe is not configured the empty packets would be sent, which is not harmful. The error can only be triggered when Unbound is configured with assertions (--enable-checking or --enable-debug) and has the option interface-automatic turned on.
A remote, unauthenticated attacker can cause the Unbound daemon to crash creating a denial of service condition.
Apply an UpdateThis vulnerability has been addressed in Unbound 1.4.10. The following patch may also be applied to resolve the issue:
This vulnerability was found by Christopher Olah and reported by NLnetLabs.
This document was written by Jared Allar.
|Date First Published:||2011-05-25|
|Date Last Updated:||2011-05-25 13:15 UTC|