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new: doc: Prepare documentation for BIND 9.18.49

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Merge branch 'andoni/prepare-documentation-for-bind-9.18.49' into 'v9.18.49-release'

See merge request isc-private/bind9!1032
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Andoni Duarte 2026-05-08 14:36:53 +00:00
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@ -18,6 +18,7 @@ Changelog
development. Regular users should refer to :ref:`Release Notes <relnotes>`
for changes relevant to them.
.. include:: ../changelog/changelog-9.18.49.rst
.. include:: ../changelog/changelog-9.18.48.rst
.. include:: ../changelog/changelog-9.18.47.rst
.. include:: ../changelog/changelog-9.18.46.rst

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doc/arm/notes.rst
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@ -45,6 +45,7 @@ The list of known issues affecting the latest version in the 9.18 branch can be
found at
https://gitlab.isc.org/isc-projects/bind9/-/wikis/Known-Issues-in-BIND-9.18
.. include:: ../notes/notes-9.18.49.rst
.. include:: ../notes/notes-9.18.48.rst
.. include:: ../notes/notes-9.18.47.rst
.. include:: ../notes/notes-9.18.46.rst

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@ -0,0 +1,226 @@
.. Copyright (C) Internet Systems Consortium, Inc. ("ISC")
..
.. SPDX-License-Identifier: MPL-2.0
..
.. This Source Code Form is subject to the terms of the Mozilla Public
.. License, v. 2.0. If a copy of the MPL was not distributed with this
.. file, you can obtain one at https://mozilla.org/MPL/2.0/.
..
.. See the COPYRIGHT file distributed with this work for additional
.. information regarding copyright ownership.
BIND 9.18.49
------------
Security Fixes
~~~~~~~~~~~~~~
- Fix outgoing zone transfers' quota issue. ``694648e14b``
Unauthorized clients could consume outgoing zone transfers quota and
block authorized zone transfer clients. This has been fixed.
:gl:`#3589`
- [CVE-2026-3592] Limit resolver server list size. ``5abfbc2663``
When resolving a domain with many nameservers that share overlapping
IP addresses (e.g., 10 NS records all pointing at the same set of
addresses), BIND could previously waste time querying duplicate
addresses and build up excessively large server lists. Deduplicate
addresses in the resolver's server list so that each unique IP is only
queried once per resolution attempt, regardless of how many NS records
point to it and cap the number of addresses stored per nameserver name
to 6 (combined A and AAAA), preventing memory and CPU overhead from
domains with unusually large NS/glue sets. :gl:`#5641`
- [CVE-2026-3039] Fix GSS-API resource leak. ``03ce21cf30``
Fixed a memory leak where each GSS-API TKEY negotiation leaked a
security context inside the GSS library. An unauthenticated attacker
could exhaust server memory by sending repeated TKEY queries to a
server with tkey-gssapi-keytab configured. The leaked memory was
allocated by the GSS library, bypassing BIND's memory accounting.
Multi-round GSS-API negotiation (GSS_S_CONTINUE_NEEDED) is now
rejected, as BIND never supported it correctly and Kerberos/SPNEGO
completes in a single round.
Also implemented missing RFC 3645 requirement: the client now verifies
that mutual authentication and integrity flags are granted by the
GSS-API mechanism (Section 3.1.1). :gl:`#5752`
- [CVE-2026-5950] Avoid unbounded recursion loop. ``43d173797e``
A bug during bad server handling could cause the resolver to enter an
infinite loop, continuously sending queries to an upstream server with
no exit condition, until the resolver query timeout was hit. This has
been fixed.
ISC would like to thank Billy Baraja (BielraX) for bringing this issue
to our attention. :gl:`#5804`
- [CVE-2026-5946] Disable recursion, UPDATE, and NOTIFY for non-IN
views. ``7ce6ce37b1``
Recursion, dynamic updates (UPDATE), and zone change notifications
(NOTIFY) are now disabled for views with a class other than IN (such
as CHAOS or HESIOD); authoritative service for non-IN zones (e.g.
version.bind in class CHAOS) continues to work as before. Servers
configured with recursion yes in a non-IN view will log a warning at
startup, and named-checkconf flags the same condition. UPDATE and
NOTIFY messages that specify the meta-classes ANY or NONE in the
question section are now rejected with FORMERR.
This addresses a set of closely related security issues collectively
identified as CVE-2026-5946. ISC would like to thank Mcsky23 for
bringing these issues to our attention.
Feature Changes
~~~~~~~~~~~~~~~
- Revert isdelegation() to return boolean value again. ``83e5e8c4d0``
:gl:`#5838` :gl:`!11803`
- Fix CPU spikes and slow queries when cache approaches memory limit.
``874a19c71b``
When the cache grew close to the configured max-cache-size, every
subsequent entry triggered all worker threads to run cache cleanup at
once, causing CPU spikes and a drop in query throughput. Cleanup is
now spread probabilistically across inserts as memory approaches the
limit, so the work is distributed evenly instead of piling up at the
threshold.
Bug Fixes
~~~~~~~~~
- Fix named crash when processing SIG records in dynamic updates.
``df77c239ac``
Previously, :iscman:`named` could abort if a client sent a dynamic
update containing a SIG record (the legacy signature type) to a zone
configured with an update-policy. The function `dns_db_findrdataset`
had an incorrect requirements prerequisite that prevented SIG records
being looked up, which was triggered as part of processing an UPDATE
request and could be triggered remotely by any client permitted to
send updates. This has been fixed by ensuring that SIG records are
handled consistently with RRSIG records during update processing.
:gl:`#5818` :gl:`!11877`
- Fix zone verification of NSEC3 signed zones. ``3a2e16ae65``
Previously, when computing the compressed bitmap during verification
of an NSEC3-signed zone, an undersized buffer was used that resulted
in an out-of-bounds write if there were too many active windows in the
bitmap. This impacted mirror zones which are NSEC3-signed,
`dnssec-signzone` and `dnssec-verifyzone`. This has been fixed.
:gl:`#5834` :gl:`!11834`
- Prevent a crash when using both dns64 and filter-aaaa. ``891d055efc``
An assertion failure could be triggered if both `dns64` and the
`filter-aaaa` plugin were in use simultaneously. This happened if the
plugin triggered a second recursion process, which then attempted to
store DNS64 state information in a pointer that had already been set
by the original recursion process. This has been fixed. :gl:`#5854`
:gl:`!11968`
- Remove unnecessary dns_name_free call. ``46aa4fd08d``
When processing a catalog zone member's primaries definition and there
is a TXT record containing an invalid name TSIG key name,
dns_name_free was incorrectly called triggering an assertion. This has
been fixed. :gl:`#5858` :gl:`!11849`
- Tidy up the cleanup path in check_signer() ``03af408476``
When check_signer() processed a DNSKEY whose public-key data could not
be parsed, the early return on the parse error skipped the cleanup of
the cloned signature rdataset. In every code path that currently
reaches this function the cloned rdataset holds no resources, so no
memory was actually leaked, but the cleanup is restructured so the
parse and the iteration cannot diverge again. :gl:`#5869` :gl:`!11960`
- Prevent malicious DNSSEC zones from exhausting validator CPU.
``784725ef85``
A DNSSEC-signed zone could publish a DNSKEY with an unusually large
RSA public exponent and force any validator resolving names in that
zone to spend disproportionate CPU verifying signatures. The
validator now rejects such DNSKEYs, matching the limit already applied
to keys read from files or HSMs. :gl:`#5881` :gl:`!11924`
- Fix inverted gethostname() check in rndc status. ``c874e39a23``
The replacement of named_os_gethostname() with raw gethostname()
inverted the success check: the "localhost" fallback runs on success,
and on failure the uninitialized hostname buffer is read by
snprintf(), leaking stack memory via the rndc status reply.
:gl:`#5889` :gl:`!11883`
- Fix rndc-confgen aborting on HMAC-SHA-384/512 keys above 512 bits.
``739e79592d``
`rndc-confgen -A hmac-sha384` and `-A hmac-sha512` documented a `-b`
range of 1..1024, but any value above 512 aborted on hardened builds
instead of producing a key. The full advertised range now works.
:gl:`#5903` :gl:`!11911`
- Prevent crafted queries from degrading RRL performance. ``e81855244d``
With response rate limiting enabled, an attacker sending queries from
many spoofed source addresses could steer entries into the same slot
of the internal rate-limit table and slow down query processing on the
affected server. The table now uses a per-process keyed hash so the
placement of entries cannot be predicted or influenced from the
network. :gl:`#5906` :gl:`!11953`
- Fix swapped arguments in redirect2() single-label branch.
``9a969bf1bc``
On a recursive resolver with nxdomain-redirect configured, an NXDOMAIN
result for a query whose qname is the root could corrupt the view's
nxdomain-redirect target, after which the redirect feature stopped
working for every subsequent query in that view until named was
restarted. :gl:`#5908` :gl:`!11914`
- Fix a bug in allow-query/allow-transfer catalog zone custom
properties. ``9e5a52e6fa``
The :iscman:`named` process could terminate unexpectedly when
processing a catalog zone with an invalid ``allow-query`` or
``allow-transfer`` custom property (i.e. having a non-APL type)
coexisting with the valid property. This has been fixed. :gl:`#5941`
:gl:`!11976`
- Fix a memory leak issue in the catalog zones. ``0b5874d3e1``
The :iscman:`named` process could leak small amounts of memory when
processing a catalog zone entry which had defined custom primary
servers with TSIG keys using both the regular ``primaries`` custom
property syntax and the legacy alternative syntax (``masters``) at the
same time. This has been fixed. :gl:`#5943` :gl:`!11974`
- Fix suppressed missing-glue check in named-checkzone. ``598277fe03``
named-checkzone and named-checkconf -z silently skipped the
missing-glue check for any NS name that had already triggered an
extra-AAAA-glue warning, so zones missing required A glue could pass
validation and be deployed with broken delegations. :gl:`!11906`
- Pass empty string instead of NULL to ns_client_dumpmessage()
``d489d825dc``
Pass "" instead of NULL to ns_client_dumpmessage() to get the log
message printed.
- Reject record sets too large to serve in DNS. ``ab3d96b3e3``
When BIND was asked to store a record set whose total size exceeds
what fits in a DNS message, it would allocate memory and build the
structure, then fail later at response time. Such oversized record
sets are now rejected at the time of storage with an error, avoiding
wasted work on data that can never be served. :gl:`!11965`

192
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@ -0,0 +1,192 @@
.. Copyright (C) Internet Systems Consortium, Inc. ("ISC")
..
.. SPDX-License-Identifier: MPL-2.0
..
.. This Source Code Form is subject to the terms of the Mozilla Public
.. License, v. 2.0. If a copy of the MPL was not distributed with this
.. file, you can obtain one at https://mozilla.org/MPL/2.0/.
..
.. See the COPYRIGHT file distributed with this work for additional
.. information regarding copyright ownership.
Notes for BIND 9.18.49
----------------------
Security Fixes
~~~~~~~~~~~~~~
- Limit resolver server list size. :cve:`2026-3592`
When resolving a domain with many nameservers that shared overlapping
IP addresses (e.g., 10 NS records all pointing at the same set of
addresses), BIND could previously waste time querying duplicate
addresses and build up excessively large server lists. Addresses in
the resolver's server list are now deduplicated so that each unique IP is only
queried once per resolution attempt, regardless of how many NS records
point to it. The number of addresses stored per nameserver name
is also now capped at six (combined A and AAAA), preventing memory and CPU overhead from
domains with unusually large NS/glue sets.
ISC would like to thank Shuhan Zhang from Tsinghua University for
reporting this issue. :gl:`#5641`
- Fix GSS-API resource leak. :cve:`2026-3039`
A memory leak was fixed where each GSS-API TKEY negotiation leaked a
security context inside the GSS library. An unauthenticated attacker
could exhaust server memory by sending repeated TKEY queries to a
server with :any:`tkey-gssapi-keytab` configured. The leaked memory was
allocated by the GSS library, bypassing BIND's memory accounting.
Multi-round GSS-API negotiation (GSS_S_CONTINUE_NEEDED) is now
rejected, as BIND never supported it correctly and Kerberos/SPNEGO
completes in a single round.
ISC would like to thank Vitaly Simonovich for bringing this
vulnerability to our attention. :gl:`#5752`
- Disable recursion, UPDATE, and NOTIFY for non-IN views.
:cve:`2026-5946`
Recursion, dynamic updates (UPDATE), and zone change notifications
(NOTIFY) are now disabled for views with a class other than IN (such
as CHAOS or HESIOD); authoritative service for non-IN zones (e.g.
version.bind in class CHAOS) continues to work as before. Servers
configured with :namedconf:ref:`recursion yes; <recursion>`
in a non-IN view log a warning at
startup, and :iscman:`named-checkconf` flags the same condition. UPDATE and
NOTIFY messages that specify the meta-classes ANY or NONE in the
question section are now rejected with FORMERR.
This addresses a set of closely related security issues collectively
identified as CVE-2026-5946. ISC would like to thank Mcsky23 for
bringing these issues to our attention. :gl:`#5784`
- Avoid unbounded recursion loop. :cve:`2026-5950`
A bug during bad server handling could cause the resolver to enter an
infinite loop, continuously sending queries to an upstream server with
no exit condition, until the resolver query timeout was hit. This has
been fixed.
ISC would like to thank Billy Baraja (BielraX) for bringing this issue
to our attention. :gl:`#5804`
- Fix outgoing zone transfers' quota issue.
Unauthorized clients could consume the entire outgoing zone-transfer quota and
block authorized zone transfer clients. This has been fixed.
:gl:`#3589`
Feature Changes
~~~~~~~~~~~~~~~
- Fix CPU spikes and slow queries when cache approaches memory limit.
Cache cleanup is now spread probabilistically to avoid CPU usage spikes and a
drop in query throughput. :gl:`#5891`
Bug Fixes
~~~~~~~~~
- Fix :iscman:`named` crash when processing SIG records in dynamic updates.
Previously, :iscman:`named` could abort if a client sent a dynamic
update containing a SIG record (the legacy signature type) to a zone
configured with an update-policy. The function `dns_db_findrdataset`
had an incorrect requirements prerequisite that prevented SIG records
from being looked up, which was triggered as part of processing an UPDATE
request and could be triggered remotely by any client permitted to
send updates. This has been fixed by ensuring that SIG records are
handled consistently with RRSIG records during update processing.
:gl:`#5818`
- Fix :option:`rndc modzone` behavior for a zone in named.conf.
If a zone was present in the configuration file and not originally
added by :option:`rndc addzone`, :option:`rndc modzone` for that zone would succeed
once but subsequent :option:`rndc modzone` attempts would fail. This has been
fixed. :gl:`#5826`
- Fix zone verification of NSEC3 signed zones.
Previously, when computing the compressed bitmap during verification
of an NSEC3-signed zone, an undersized buffer was used that resulted
in an out-of-bounds write if there were too many active windows in the
bitmap. This impacted the mirror zones which are NSEC3-signed,
:iscman:`dnssec-signzone` and :iscman:`dnssec-verify`. This has been fixed.
:gl:`#5834`
- Prevent a crash when using both :any:`dns64` and :any:`filter-aaaa`.
An assertion failure could be triggered if both :any:`dns64` and the
:any:`filter-aaaa` plugin were in use simultaneously. This happened if the
plugin triggered a second recursion process, which then attempted to
store DNS64 state information in a pointer that had already been set
by the original recursion process. This has been fixed. :gl:`#5854`
- Fixed an assertion failure when processing catalog zones.
If a TXT record containing an invalid name TSIG key name was found
when processing a catalog zone member's primaries definition,
``dns_name_free`` was incorrectly called, triggering an assertion. This has
been fixed. :gl:`#5858`
- Prevent malicious DNSSEC zones from exhausting validator CPU.
A DNSSEC-signed zone could publish a DNSKEY with an unusually large
RSA public exponent and force any validator resolving names in that
zone to spend disproportionate CPU verifying signatures. The
validator now rejects such DNSKEYs, matching the limit already applied
to keys read from files or HSMs. :gl:`#5881`
- Fix :iscman:`rndc-confgen` aborting on HMAC-SHA-384/512 keys above 512 bits.
:iscman:`rndc-confgen` (with either ``-A hmac-sha384`` or
``-A hmac-sha512``) previously documented a ``-b``
range of 1..1024, but any value above 512 aborted on hardened builds
instead of producing a key. The full advertised range now works.
:gl:`#5903`
- Prevent crafted queries from degrading RRL performance.
With response rate limiting enabled, an attacker sending queries from
many spoofed source addresses could steer entries into the same slot
of the internal rate-limit table and slow down query processing on the
affected server. The table now uses a per-process keyed hash so the
placement of entries cannot be predicted or influenced from the
network. :gl:`#5906`
- Fix a bug in :any:`allow-query`/:any:`allow-transfer` catalog zone custom
properties.
The :iscman:`named` process could terminate unexpectedly when
processing a catalog zone with an invalid :any:`allow-query` or
:any:`allow-transfer` custom property (i.e. having a non-APL type)
coexisting with the valid property. This has been fixed. :gl:`#5941`
- Fix a memory leak issue in catalog zones.
The :iscman:`named` process could leak small amounts of memory when
processing a catalog zone entry which had defined custom primary
servers with TSIG keys, if both the regular ``primaries`` custom
property syntax and the legacy alternative syntax (``masters``) were used at the
same time. This has been fixed. :gl:`#5943`
- Fix suppressed missing-glue check in :iscman:`named-checkzone`.
:iscman:`named-checkzone` and :option:`named-checkconf -z` silently
skipped the missing-glue check for any NS name that had already
triggered an extra-AAAA-glue warning, so zones missing required A glue
could pass validation and be deployed with broken delegations.
:gl:`!11899`
- Reject record sets too large to serve in DNS.
When BIND was asked to store a record set whose total size exceeded
what fit in a DNS message, it would allocate memory and build the
structure, then fail later at response time. Such oversized record
sets are now rejected at the time of storage with an error, avoiding
wasted work on data that can never be served. :gl:`!11963`