--- /dev/null
+.. 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 9.20.23
+----------------------
+
+Security Fixes
+~~~~~~~~~~~~~~
+
+- Fix outgoing zone transfers' quota issue.
+
+ 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.
+
+ 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.
+
+ 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.
+
+ 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-2026-3593] Add system test for HTTP/2 SETTINGS frame flood.
+
+ A use-after-free vulnerability in the DNS-over-HTTPS implementation
+ could cause named to crash when a client sends a flood of HTTP/2
+ SETTINGS frames while a DoH response is being written. This affects
+ servers with DoH (DNS-over-HTTPS) enabled.
+
+ ISC would like to thank Naresh Kandula Parmar (Nottiboy) for reporting
+ this.
+
+ For: #5755
+
+- [CVE-2026-5946] Disable recursion, UPDATE, and NOTIFY for non-IN
+ views.
+
+ 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
+~~~~~~~~~~~~~~~
+
+- Fix CPU spikes and slow queries when cache approaches memory limit.
+
+ 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
+~~~~~~~~~
+
+- Use the zone file's basename as origin in DNSSEC tools.
+
+ In `dnssec-signzone` and `dnssec-verify`, when the zone origin is not
+ specified using the `-o` parameter, the default behavior is to try to
+ sign using the zone's file name as the origin. So, for example,
+ `dnssec-signzone -S example.com` will work, so long as the file name
+ matches the zone name.
+
+ This now also works if the zone is in a different directory. For
+ example, `dnssec-signzone -S zones/example.com` will set the origin
+ value to `example.com`. :gl:`#5678`
+
+- Fix a possible race condition during zone transfers.
+
+ The :iscman:`named` process could terminate unexpectedly when
+ processing an IXFR message during a zone transfer. This has been
+ fixed. :gl:`#5767`
+
+- Fix 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
+ 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 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 mirror zones which are NSEC3-signed,
+ `dnssec-signzone` and `dnssec-verifyzone`. This has been fixed.
+ :gl:`#5834`
+
+- Prevent a crash when using both dns64 and filter-aaaa.
+
+ 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`
+
+- Remove unnecessary dns_name_free call.
+
+ 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`
+
+- 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 rndc-confgen aborting on HMAC-SHA-384/512 keys above 512 bits.
+
+ `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`
+
+- 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`
+
+- Prevent rare named crash when notifies are cancelled.
+
+ Under heavy load, named could occasionally crash when a queued
+ outbound notify or zone refresh was cancelled at the moment it was
+ being sent — for example, while a zone was being reloaded or removed.
+ The race that caused the crash is now prevented. :gl:`#5915`
+
+- Stop delv from aborting on a malformed query name.
+
+ delv aborts with SIGABRT instead of exiting cleanly when given a query
+ name that fails wire-format conversion (e.g. a label longer than 63
+ octets). After this change delv prints the parse error and exits with
+ a normal failure code. :gl:`#5916`
+
+- Fix a crash when reconfiguring while an NTA is being rechecked.
+
+ When named was reconfigured or shut down while a negative trust anchor
+ was being rechecked against authoritative servers, the in-flight
+ recheck could outlive the view that owned it and cause `named` to
+ crash. This has been fixed. :gl:`#5938`
+
+- Fix a bug in allow-query/allow-transfer catalog zone custom
+ properties.
+
+ 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`
+
+- Fix a memory leak issue in the 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 using both the regular ``primaries`` custom
+ property syntax and the legacy alternative syntax (``masters``) at the
+ same time. This has been fixed. :gl:`#5943`
+
+- Fix suppressed missing-glue check in named-checkzone.
+
+ 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.
+
+- Implement seamless outgoing TCP connection reuse.
+
+ The resolver can and will reuse outgoing TCP connections to the same
+ host, as recommended by RFC 7766. This prevents a whole class of
+ attacks that abuse the fact that establishing a TCP connection is
+ expensive and it is fairly easy to deplete the outgoing TCP ports by
+ putting them into TIME_WAIT state.
+
+ The number of pipelined queries per connection is capped at 256 to
+ limit the impact of a connection drop.
+
+- Reject record sets too large to serve in DNS.
+
+ 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.
+
+
projects / thirdparty / bind9.git / commitdiff
