--- /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 9.21.10
+----------------------
+
+Security Fixes
+~~~~~~~~~~~~~~
+
+- [CVE-2025-40777] Fix a possible assertion failure when using the
+ 'stale-answer-client-timeout 0' option.
+
+ In specific circumstances the :iscman:`named` resolver process could
+ terminate unexpectedly when stale answers were enabled and the
+ ``stale-answer-client-timeout 0`` configuration option was used. This
+ has been fixed. :gl:`#5372`
+
+New Features
+~~~~~~~~~~~~
+
+- "Add code paths to fully support PRIVATEDNS and PRIVATEOID keys"
+
+ Added support for PRIVATEDNS and PRIVATEOID key usage. Added
+ PRIVATEOID test algorithms using the assigned OIDs for RSASHA256 and
+ RSASHA512.
+
+ Added code to support proposed DS digest types that encode the
+ PRIVATEDNS and PRIVATEOID identifiers at the start of the digest field
+ of the DS record. This code is disabled by default. :gl:`#3240`
+
+- Add "named-makejournal" tool.
+
+ The `named-makejournal` tool reads two zone files for the same domain,
+ compares them, and generates a journal file from the differences.
+ :gl:`#5164`
+
+- Add support to set and display the CO flag.
+
+ Add support to display the CO (Compact denial of existence Ok flag)
+ when displaying messages.
+
+ Add support to set the CO flag when making queries in dig (+coflag).
+ :gl:`#5319`
+
+Bug Fixes
+~~~~~~~~~
+
+- Fix the default interface-interval from 60s to 60m.
+
+ When the interface-interval parser was changed from uint32 parser to
+ duration parser, the default value stayed at plain number `60` which
+ now means 60 seconds instead of 60 minutes. The documentation also
+ incorrectly states that the value is in minutes. That has been fixed.
+ :gl:`#5246`
+
+- Fix purge-keys bug when using views.
+
+ Previously, when a DNSSEC key was purged by one zone view, other zone
+ views would return an error about missing key files. This has been
+ fixed. :gl:`#5315`
+
+- Use IPv6 queries in delv +ns.
+
+ `delv +ns` invokes the same code to perform name resolution as
+ `named`, but it neglected to set up an IPv6 dispatch object first.
+ Consequently, it was behaving more like `named -4`. It now sets up
+ dispatch objects for both address families, and performs resolver
+ queries to both v4 and v6 addresses, except when one of the address
+ families has been suppressed by using `delv -4` or `delv -6`.
+ :gl:`#5352`
+
+