An unusually-formed answer containing a DS resource record could trigger an assertion failure. While the combination of properties which triggers the assertion should not occur in normal traffic, it is potentially possible for the assertion to be triggered deliberately by an attacker sending a specially-constructed answer having the required properties.

This vulnerability occurs during the processing of an answer packet received in response to a query. As a result, recursive servers are at the greatest risk; authoritative servers are at risk only to the extent that they perform a limited set of queries.

This description is borrowed from the upstream advisory.

query.c in ISC BIND 9.0.x through 9.6.x, 9.4-ESV through 9.4-ESV-R5, 9.6-ESV through 9.6-ESV-R5, 9.7.0 through 9.7.4, 9.8.0 through 9.8.1, and 9.9.0a1 through 9.9.0b1 allows remote attackers to cause a denial of service (assertion failure and named exit) via unknown vectors related to recursive DNS queries, error logging, and the caching of an invalid record by the resolver.

Unspecified vulnerability in ISC BIND 9 9.6.x before 9.6-ESV-R4-P3, 9.7.x before 9.7.3-P3, and 9.8.x before 9.8.0-P4 allows remote attackers to cause a denial of service (named daemon crash) via a crafted UPDATE request.

Common Vulnerabilities and Exposures assigned an identifier CVE-2011-1910 to the following vulnerability:

A BIND 9 DNS server set up to be a caching resolver is vulnerable to a user querying a domain with very large resource record sets (RRSets) when trying to negatively cache a response. This can cause the BIND 9 DNS server (named process) to crash.

http://www.isc.org/software/bind/advisories/cve-2011-1910

ISC BIND 9.7.1 through 9.7.2-P3, when configured as an authoritative server, allows remote attackers to cause a denial of service (deadlock and daemon hang) by sending a query at the time of (1) an IXFR transfer or (2) a DDNS update.

ISC BIND 9.x before 9.7.6-P4, 9.8.x before 9.8.3-P4, 9.9.x before 9.9.1-P4, and 9.4-ESV and 9.6-ESV before 9.6-ESV-R7-P4 allows remote attackers to cause a denial of service (named daemon hang) via unspecified combinations of resource records.

ISC BIND 9.x before 9.7.6-P3, 9.8.x before 9.8.3-P3, 9.9.x before 9.9.1-P3, and 9.4-ESV and 9.6-ESV before 9.6-ESV-R7-P3 allows remote attackers to cause a denial of service (assertion failure and named daemon exit) via a query for a long resource record.

ISC BIND 9.4.x, 9.5.x, 9.6.x, and 9.7.x before 9.7.6-P2; 9.8.x before 9.8.3-P2; 9.9.x before 9.9.1-P2; and 9.6-ESV before 9.6-ESV-R7-P2, when DNSSEC validation is enabled, does not properly initialize the failing-query cache, which allows remote attackers to cause a denial of service (assertion failure and daemon exit) by sending many queries.

The RFC 5011 implementation in rdata.c in ISC BIND 9.7.x and 9.8.x before 9.8.5-P2, 9.8.6b1, 9.9.x before 9.9.3-P2, and 9.9.4b1, and DNSco BIND 9.9.3-S1 before 9.9.3-S1-P1 and 9.9.4-S1b1, allows remote attackers to cause a denial of service (assertion failure and named daemon exit) via a query with a malformed RDATA section that is not properly handled during construction of a log message, as exploited in the wild in July 2013.

libdns in ISC BIND 9.7.x and 9.8.x before 9.8.4-P2, 9.8.5 before 9.8.5b2, 9.9.x before 9.9.2-P2, and 9.9.3 before 9.9.3b2 on UNIX platforms allows remote attackers to cause a denial of service (memory consumption) via a crafted regular expression, as demonstrated by a memory-exhaustion attack against a machine running a named process.

ISC BIND 9.0.x through 9.8.x, 9.9.0 through 9.9.6, and 9.10.0 through 9.10.1 does not limit delegation chaining, which allows remote attackers to cause a denial of service (memory consumption and named crash) via a large or infinite number of referrals.

Race condition in resolver.c in named in ISC BIND 9.9.8 before 9.9.8-P2 and 9.10.3 before 9.10.3-P2 allows remote attackers to cause a denial of service (INSIST assertion failure and daemon exit) via unspecified vectors.

db.c in named in ISC BIND 9.x before 9.9.8-P2 and 9.10.x before 9.10.3-P2 allows remote attackers to cause a denial of service (REQUIRE assertion failure and daemon exit) via a malformed class attribute.

name.c in named in ISC BIND 9.7.x through 9.9.x before 9.9.7-P1 and 9.10.x before 9.10.2-P2, when configured as a recursive resolver with DNSSEC validation, allows remote attackers to cause a denial of service (REQUIRE assertion failure and daemon exit) by constructing crafted zone data and then making a query for a name in that zone.

It was reported that a problem with trust anchor management can cause named to crash, affecting BIND versions 9.7.0+.

ISC developers believe that it will be very difficult for this to be triggered in most cases, requiring DNSSEC validation amongst other factors.

ISC will not be producing patches specifically for BIND 9.8 or BIND 9.6-ESV, both of which are beyond their End of Life (EOL) and are no longer supported by ISC.

Patches that correct this issue for ISC BIND 9.10.1 and ISC BIND 9.9.6 are attached to this Bugzilla.

A packet with a malformed options section can be used to deliberately trigger an assertion failure affecting versions of BIND which do not contain change #3548.

A server vulnerable to this defect can be forced to exit with an assertion failure if it receives a malformed packet. Authoritative and recursive servers are both vulnerable.

https://source.isc.org/cgi-bin/gitweb.cgi?p=bind9.git;a=blob;f=CHANGES has more information on change #3548. The commit corresponding to this change is https://source.isc.org/cgi-bin/gitweb.cgi?p=bind9.git;a=commitdiff;h=4adf97c32fcca7d00e5756607fd045f2aab9c3d4.