| 1.1.1.1 |
| 06-Sep-2025 |
christos | Import unbound-1.23.1 (previous was 1.19.1)
Unbound 1.23.1
July 16, 2025
This security release fixes the Rebirthday Attack CVE-2025-5994.
This re-opens up resolvers to a birthday paradox, for EDNS client subnet
servers that respond with non-ECS answers. It only affects Unbound when
compiled with --enable-subnet, and subnetmod is enabled with config
options that send ECS information to upstream servers.
The CVE is described here
https://nlnetlabs.nl/downloads/unbound/CVE-2025-5994.txt
We would like to thank Xiang Li (AOSP Lab, Nankai University) for
discovering and responsibly disclosing the vulnerability.
Bug Fixes:
Fix RebirthDay Attack CVE-2025-5994, reported by Xiang Li from
AOSP Lab Nankai University.
Unbound 1.23.0
Apr 24, 2025
This release features changed defaults, fast reload, redis replica,
DNS Error Reporting, and bug fixes.
The fast reload is a feature that is listed as experimental. With
unbound-control fast_reload the server can read the new config in
a thread, and when done only briefly pauses the server to update the
settings. This uses double memory, for like zones from disk or config
that is loaded. It only pauses the server, for like less than a second,
so DNS service is not interrupted by the reload of config. A lot of
config items can be changed, but not all. It has options to print
more information, or memory usage, and there is a list of config
options in the man page.
The redis replica support allows for a redis backend to use a redis
replica. The read commands are sent to the redis replica host, while
the write commands are sent to the redis server. So with several
replicas there can be more readers that all write to the redis server.
With DNS error reporting, RFC9567, enabled with
dns-error-reporting: yes, this uses the error reporting agent to send
failure reports to. The number of error reporting queries is output in
the statistics as num.dns_error_reports.
Some defaults are changed in this release. The resolver.arpa. and
service.arpa. zones are added to the default locally served zones,
this can be disabled with a nodefault local zone. The default for
max-global-quota has changed to 200, after operational feedback.
The defaults from RFC8767 are used by serve-expired-client-timeout
on 1800 milliseconds and serve-expired-ttl on 86400 seconds. If
Unbound is compiled with edns subnet, the default for module-config
is no longer altered, so that compilation with subnet does not
interfere when the server does not use subnet. When edns subnet needs
to be enabled, module-config: "subnetcache validator iterator" should
be explicitly set as configuration in the server: section.
If edns subnet is enabled, the default for
module-config is no longer altered, so that compilation with subnet
does not interfere when the server does not use subnet. When edns subnet
is in use, also module-config: "subnetcache validator iterator" should
be set as configuration in the server: section.
The RC2 has fixes for building on Solaris and portability to Windows,
and fixes a memory leak for DoH.
Features
Increase the default of max-global-quota to 200 from 128 after
operational feedback. Still keeping the possible amplification
factor (CAMP related issues) in the hundreds.
Fix #1175: serve-expired does not adhere to secure-by-default
principle. The default value of serve-expired-client-timeout
is set to 1800 as suggested by RFC8767.
For #1175, the default value of serve-expired-ttl is set to 86400
(1 day) as suggested by RFC8767.
For #1207: [FR] Support for RESINFO RRType 261 (RFC9606), add
LDNS_RR_TYPE_RESINFO similar to LDNS_RR_TYPE_TXT.
Add resolver.arpa and service.arpa to the default locally served
zones.
Merge #1042: Fast Reload. The unbound-control fast_reload is added.
It reads changed config in a thread, then only briefly pauses the
service threads, that keep running. DNS service is only interrupted
briefly, less than a second.
Merge #1019: Redis read-only replica support.
Introduces new 'redis-replica-*' options for the Redis cache backend.
Merge #902: DNS Error Reporting (RFC 9567). Introduces new
configuration option 'dns-error-reporting' and new statistics for
'num.dns_error_reports'.
Bug Fixes
Fix #1154: Tag Incorrectly Applying for Other Interfaces
Using the Same IP. This fix is not for 1.22.0.
Fix #1163: Typos in unbound.conf documentation.
Merge #1159: Stats for discard-timeout and wait-limit.
Add test case for #1159.
Some clean up for stat_values.test.
Merge #1170 from Melroy van den Berg, Fix chroot manpage
description.
Merge #1157 from Liang Zhu, Fix heap corruption when calling
ub_ctx_delete in Windows.
Fix redis that during a reload it does not fail if the redis
server does not connect or does not respond. It still logs the
errors and if the server is up checks expiration features.
Merge #1167: Makefile.in: fix occasional parallel build failures
around bison rule.
Fix SETEX check during Redis (re)initialization.
Fix for the serve expired DNSSEC information fix, it would not allow
current delegation information be updated in cache. The fix allows
current delegation and validation recursion information to be
updated, but as a consequence no longer has certain expired
information around for later dnssec valid expired responses.
Fix to log redis timeout error string on failure.
More descriptive text for 'harden-algo-downgrade'.
Complete fix for max-global-quota to 200.
Fix #1183: the data being used is released in method
nsec3_hash_test_entry.
Fix for #1183: release nsec3 hashes per test file.
Merge #1169 from Sergey Kacheev, fix: lock-free counters for
auth_zone up/down queries.
Fix comparison to help static analyzer.
For #1175, update serve-expired tests.
Merge #1189: Fix the dname_str method to cause conversion errors
when the domain name length is 255.
Merge #1197: dname_str() fixes.
Merge #1198: Fix log-servfail with serve expired and no useful cache
contents.
Safeguard alias loop while looking in the cache for expired answers.
Merge #1187: Create the SSL_CTX for QUIC before chroot and privilege
drop.
Fix typo in log_servfail.tdir test.
Merge #1204: ci: set persist-credentials: false for actions/checkout
per zizmor suggestion.
Merge #1174: Serve expired cache update fixes. Fixes a regression bug
with serve-expired that appeared in 1.22.0 and would not allow the
iterator to update the cache with not-yet-validated entries resulting
in increased outgoing traffic.
Merge #1214: Use TCP_NODELAY on TLS sockets to speed up the TLS
handshake.
Fix #1213: Misleading error message on default access control causing
refuse.
Merge #1221: Consider auth zones when checking for forwarders.
Merge #1222: Unique DoT and DoH SSL contexts to allow for different
ALPN.
Create the quic SSL listening context only when needed.
Fix compile of interface check code when dnscrypt or quic is
disabled.
Fix encoding of RR type ATMA.
Fix to check length in ATMA string to wire.
Merge #1229: check before use daemon->shm_info.
Use the same interface listening port discovery code for all needed
protocols.
Port to string only when needed before getaddrinfo().
Do not open unencrypted channels next to encrypted ones on the same
port.
Merge #1224 from Theo Buehler: Do not use DSA API unless USE_DSA is
set.
Merge #1220 from Petr Men#�k, Add unbound members group access to
control key.
Make the default value of module-config "validator iterator"
regardless of compilation options. --enable-subnet would implicitly
change the value to enable the subnetcache module by default in the
past.
Fix #986: Resolving sas.com with dnssec-validation fails though
signed delegations seem to be (mostly) correct.
Consider reconfigurations when calculating the still_useful_timeout
for servers in the infrastructure cache.
Fix static analysis report about unhandled EOF on error conditions
when reading anchor key files.
Merge #1241: Fix infra-keep-probing for low infra-cache-max-rtt
values.
Fix hash calculation for cachedb to ignore case. Previously, cached
records there were only relevant for same case queries (if not
already in Unbound's internal cache).
Merge #1243: Do not shadow tm on line 236.
Merge #1238: Prefer SOURCE_DATE_EPOCH over actual time.
Add --help output description for the SOURCE_DATE_EPOCH variable.
Fix 'unbound-control flush_negative' when reporting removed data;
reported by David 'eqvinox' Lamparter.
Fix representation of types GPOS and RESINFO, add rdf type for
unquoted str.
Fix #1251: WSAPoll first argument cannot be NULL.
Fix for windows compile create ssl contexts.
Fix print of RR type NSAP-PTR, it is an unquoted string.
Fix #1253: Cache entries fail to be removed from Redis cachedb
backend with unbound-control flush* +c.
Fix for #1253: Fix for redis cachedb backend to expect an integer
reply for the EXPIRE command.
Fix #1254: send failed: Socket is not connected and
remote address is 0.0.0.0 port 53.
Fix #1255: Multiple pinnings to vulnerable copies of libexpat.
For #1255, for ios use an older expat version that does not require
C++11 language features.
For #1255, for ios disable building tests that require C++11.
For #1255, for ios try the latest expat version again.
Fix unit test dname log printout typecast.
Fix for ci test, expat is installed on the osx image.
iana portlist update.
Skip the unit tests for auth_tls.tdir and auth_tls_failcert.tdir.
Fix escape more characters when printing an RR type with an unquoted
string.
Enable the auth_tls.tdir and auth_tls_failcert.tdir tests.
Fix unbound-control test so it counts the new flush_negative output,
also answers the _ta probe from testns and prints command output
and skip a thread specific test when no threads are available.
Fix that ub_event has the facility to deal with callbacks for
fast reload, doq, windows-stop and dnstap.
Fix fast reload test to check if pid exists before acting on it.
Merge #1262 from markyang92, fix build with
'gcc-15 -Wbuiltin-declaration-mismatch' error in compat/malloc.c.
For #1262, ifdef is no longer needed.
Fix #1263: Exempt loopback addresses from wait-limit.
Fix wait-limit-netblock and wait-limit-cookie-netblock config parse
to allow two arguments.
Fix ub_event and include dnstap and win_svc headers.
Fix test for stat_values for wait limit default...
Unbound 1.22.0
Oct 17, 2024
This release has an option to harden against unverified glue, it
is enabled with harden-unverified-glue: yes. It was contributed
by Karthik Umashankar from Microsoft. This protects Unbound against
bad glue, that is out of zone, by performing a lookup for it.
Because it uses the original information as a last resort if nothing
works, it should not give lookup failures, and add protection.
There are options to configure the scrubbing for NS records and
the CNAME scrubbing and the max global quota lookup limit from
previous security fix releases. They can be configured with the
options iter-scrub-ns, iter-scrub-cname and max-global-quota.
For redis use, with cachedb, it is possible to specify the
timeout for the initial connection separately from the timeout
for commands. With the options redis-command-timeout: 20 and
redis-connect-timeout: 200 they can be set separately, for
a longer connect attempt, but a short command timeout to keep
resolution faster.
It is possible to log with ISO8601 format with log-time-iso: yes
this also logs time in milliseconds. Useful if the server writes to
file, syslog may have its own format.
DNS over QUIC is support is added, if compiled with libngtcp2 and
with the openssl+quic that it uses. Use --with-libngtcp2 for that,
and enable it with quic-port: 853. There is a post about it
on https://blog.nlnetlabs.nl/dns-over-quic-in-unbound [that is to
appear after the release].
Features
Add iter-scrub-ns, iter-scrub-cname and max-global-quota
configuration options.
Merge patch to fix for glue that is outside of zone, with
harden-unverified-glue, from Karthik Umashankar (Microsoft).
Enabling this option protects the Unbound resolver against bad
glue, that is unverified out of zone glue, by resolving them.
It uses the records as last resort if there is no other working
glue.
Add redis-command-timeout: 20 and redis-connect-timeout: 200,
that can set the timeout separately for commands and the
connection set up to the redis server. If they are not
specified, the redis-timeout value is used.
Fix #1144: [FR] log timestamps in ISO8601 format with timezone.
This adds the option log-time-iso: yes that logs in ISO8601
format.
Merge #871: DNS over QUIC. This adds quic-port: 853 and
quic-size: 8m that enable dnsoverquic, and the counters
num.query.quic and mem.quic in the statistics output.
The feature needs to be enabled by compiling with libngtcp2,
with --with-libngtcp2=path and libngtcp2 needs openssl+quic,
pass that with --with-ssl=path to compile unbound as well.
Bug Fixes
Fix #1126: unbound-control-setup hangs while testing for openssl
presence starting from version 1.21.0.
Add cross platform freebsd, openbsd and netbsd to github ci.
Fix for char signedness warnings on NetBSD.
Fix #1127: error: "memory exhausted" when defining more than 9994
local-zones.
Fix documentation for cache_fill_missing function.
Fix #1130: Loads of logs: "validation failure: key for validation
. is marked as invalid because of a previous" for
non-DNSSEC signed zone.
Fix that when rpz is applied the message does not get picked up by
the validator. That stops validation failures for the message.
Fix that stub-zone and forward-zone clauses do not exhaust memory
for long content.
Unit test for auth zone transfer TLS, and TLS failure.
Fix to print port number in logs for auth zone transfer activities.
Merge #1132: b.root renumbering.
Fix for #1132, adjusted unit test for change in the test file.
Fix for #1132, comment about adjusted copy of reference check.
Merge #1135: Add new IANA trust anchor.
Fix config file read for dnstap-sample-rate.
Fix alloc-size and calloc-transposed-args compiler warnings.
Fix comment to not trigger doxygen unknown command.
Fix to limit NSEC and NSEC3 TTL when aggressive nsec is
enabled (RFC9077).
Add unit test for ttl limit for aggressive nsec.
Fix and add comments in testdata/val_negcache_ttl.rpl.
Merge #1140: Fix spelling mistake in comments.
Fix doxygen warnings by commenting out CLANG_ASSISTED_PARSING,
CLANG_ADD_INC_PATHS, CLANG_OPTIONS and CLANG_DATABASE_PATH; they were
already disabled.
Fix dns64 with prefetch that the prefetch is stored in cache.
Attempt to further fix doh_downstream_buffer_size.tdir flakiness.
More clear text for prefetch and minimal-responses in the
unbound.conf man page.
Merge #1143: Fix cache update when serve expired is used. Expired
records are favored over resolution and validation failures when
serve-expired is used.
Fix negative cache NSEC3 parameter compares for zero length NSEC3
salt.
Fix unbound dnstap socket test program analyzer warnings about
unused variable assignments and variable initialization.
Fix #1149: unbound-control-setup hangs sometimes depending on
the openssl version.
Fix #1128: Cannot override tcp-upstream and tls-upstream with
forward-tcp-upstream and forward-tls-upstream.
Fix to limit NSEC TTL for messages from cachedb. Fix to limit the
prefetch ttl for messages after a CNAME with short TTL.
Fix for dnstap compile of doqclient with doq disabled.
Fix cookie_file test sporadic fails for time change during
the test.
Fix add reallocarray to alloc stats unit test, and disable
override of strdup in unbound-host, and the result of config
get option is freed properly.
Fix to disable detection of quic configured ports when quic is
not compiled in.
Fix harden-unverified-glue for AAAA cache_fill_missing lookups.
Fix contrib/aaaa-filter-iterator.patch for change in call
signature for cache_fill_missing.
Fix to display warning if quic-port is set but dnsoverquic is not
enabled when compiled.
Fix dnsoverquic to extend the number of streams when one is closed.
Fix for dnstap with dnscrypt and dnstap without dnsoverquic.
Fix for dnsoverquic and dnstap to use the correct dnstap
environment.
Unbound 1.21.1
Oct 4, 2024
This security release fixes CVE-2024-8508.
A vulnerability has been discovered in Unbound when handling replies
with very large RRsets that Unbound needs to perform name compression
for.
Malicious upstreams responses with very large RRsets can cause Unbound
to spend a considerable time applying name compression to downstream
replies. This can lead to degraded performance and eventually denial of
service in well orchestrated attacks.
The vulnerability can be exploited by a malicious actor querying Unbound
for the specially crafted contents of a malicious zone with very large
RRsets.
Before Unbound replies to the query it will try to apply name
compression which was an unbounded operation that could lock the CPU
until the whole packet was complete.
Unbound version 1.21.1 introduces a hard limit on the number of name
compression calculations it is willing to do per packet.
Packets that need more compression will result in semi-compressed
packets or truncated packets, even on TCP for huge messages, to avoid
locking the CPU for long.
This change should not affect normal DNS traffic.
We would like to thank Toshifumi Sakaguchi for discovering and
responsibly disclosing the vulnerability.
Bug Fixes:
Fix CVE-2024-8508, unbounded name compression could lead to denial of
service.
Unbound 1.21.0
Aug 15, 2024
This release has a fix for the CAMP and CacheFlush issues. They have a
low severity for Unbound, since it does not affect Unbound so much.
The Compositional Amplification (CAMP) type of attacks can lead to DoS
attacks against DNS servers. In Unbound legitimate client requests to
the resolvers under typical workload are not directly affected by CAMP
attacks. However we introduce a global quota for 128 outgoing packets
per query (and it's subqueries) that is never reset to prevent the
combination of CAMP with other amplification attacks in the future. We
would like to thank Huayi Duan, Marco Bearzi, Jodok Vieli, and Cagin
Tanir from NetSec group, ETH Zurich for discovering and notifying us
about the issue.
The CacheFlush type of attacks (NSCacheFlush, CNAMECacheFlush) try to
evict cached data by utilizing rogue zones and a steady rogue stream to
a resolver. Based on the zone, the stream, the configured cache size
and the legitimate traffic, Unbound could experience a degradation of
service if a useful entry is evicted and Unbound needs to resolve again.
As a mitigation to the NSCacheFlush attack Unbound is setting a limit
of 20 RRs in an NS RRset. We would like to thank Yehuda Afek, Anat
Bremler-Barr, Shoham Danino and Yuval Shavitt (Tel-Aviv University and
Reichman University) for discovering and notifying us about the issue.
Other fixes in this release are bug fixes. Also the unbound control
commands that flush the cache can clear both the memory and cachedb
module cache. The ipset module can use BSD pf tables. The new option
dnstap-sample-rate: 100 can be used to log 1/N messages, for use in
high volume server environments where the log server does not keep up.
The new DNSSEC key for the root, 38696 from 2024 has been added. It is
added to the default root keys in unbound-anchor. The content can be
inspected with unbound-anchor -l. Older versions of Unbound can keep
up with the root key with auto-trust-anchor-file that has RFC5011
key rollover. Also unbound-anchor can fetch the keys from the website
with a certificate if needed.
For cookie secrets, it is possible to perform rollover. The file
with cookie secret in use and the staging secret is configured
with cookie-secret-file. With the remote control the rollover can be
performed, add_cookie_secret, activate_cookie_secret, drop_cookie_secret
and print_cookie_secrets can be used for that.
Compared to the RC1, the release has a fix for module loading on Windows,
and a spelling correction.
Features
Fix #1071: [FR] Clear both in-memory and cachedb module cache with
unbound-control flush* commands.
Fix #144: Port ipset to BSD pf tables.
Add dnstap-sample-rate that logs only 1/N messages, for high volume
server environments. Thanks Dan Luther.
Add root key 38696 from 2024 for DNSSEC validation. It is added
to the default root keys in unbound-anchor. The content can be
inspected with unbound-anchor -l.
Merge #1090: Cookie secret file. Adds
cookie-secret-file: "unbound_cookiesecrets.txt" option to store
cookie secrets for EDNS COOKIE secret rollover. The remote control
add_cookie_secret, activate_cookie_secret and drop_cookie_secret
commands can be used for rollover, the command print_cookie_secrets
shows the values in use.
Bug Fixes
Fix CAMP issues with global quota. Thanks to Huayi Duan, Marco
Bearzi, Jodok Vieli, and Cagin Tanir from NetSec group, ETH Zurich.
Fix CacheFlush issues with limit on NS RRs. Thanks to Yehuda Afek,
Anat Bremler-Barr, Shoham Danino and Yuval Shavitt (Tel-Aviv
University and Reichman University).
Merge #1062: Fix potential overflow bug while parsing port in
function cfg_mark_ports.
Fix for #1062: declaration before statement, avoid print of null,
and redundant check for array size.
Fix to squelch udp connect errors in the log at low verbosity about
invalid argument for IPv6 link local addresses.
Fix when the mesh jostle is exceeded that nameserver targets are
marked as resolved, so that the lookup is not stuck on the
requestlist.
Add missing common functions to tdir tests.
Merge #1070: Fix rtt assignement for low values of
infra-cache-max-rtt.
Merge #1069: Fix unbound-control stdin commands for multi-process
Unbounds.
Fix unbound-control commands that read stdin in multi-process
operation (local_zones_remove, local_zones, local_datas_remove,
local_datas, view_local_datas_remove, view_local_datas). They will
be properly distributed to all processes. dump_cache and load_cache
are no longer supported in multi-process operation.
Remove testdata/remote-threaded.tdir. testdata/09-unbound-control.tdir
now checks both single and multi process/thread operation.
Merge #1073: fix null pointer dereference issue in function
ub_ctx_set_fwd.
Fix to print a parse error when config is read with no name for
a forward-zone, stub-zone or view.
Fix for parse end of forward-zone, stub-zone and view.
Fix for #1064: Fix that cachedb expired messages are considered
insecure, and thus can be served to clients when dnssec is enabled.
Fix #1059: Intermittent DNS blocking failure with local-zone and
always_nxdomain. Addition of local_zones dynamically via
unbound-control was not finding the zone's parent correctly.
Fix #1064: Unbound 1.20 Cachedb broken?
Fix unused variable warning on compilation with no thread support.
unbound-control-setup: check openssl availability before doing
anything, patch from Michael Tokarev.
Update patch to remove 'command' shell builtin and update error
text.
Fix to enable that SERVFAIL is cached, for a short period, for more
cases. In the cases where limits are exceeded.
Fix spelling of tcp-idle-timeout docs, from Michael Tokarev.
Merge #1078: Only check old pid if no username.
Fix #1079: tags from tagged rpz zones are no longer honored after
upgrade from 1.19.3 to 1.20.0.
Fix for #1079: fix RPZ taglist in iterator callback that no client
info is like no taglist intersection.
Fix to squelch connection reset by peer errors from log. And fix
that the tcp read errors are labeled as initial for the first calls.
Merge #1080: AddressSanitizer detection in tdir tests and memory leak
fixes.
Fix memory leak when reload_keep_cache is used and num-threads
changes.
Fix memory leak on exit for unbound-dnstap-socket; creates false
negatives during testing.
Fix memory leak in setup of dsa sig.
Fix typos for 'the the' in text.
Fix validation for repeated use of a DNAME record.
Add unit test for validation of repeated use of a DNAME record.
Fix #1091: Build fails with OpenSSL >= 3.0 built with
OPENSSL_NO_DEPRECATED.
Fix #1092: Ubuntu 22.04 Jammy fails to compile unbound 1.20.0; by
adding helpful text for the Python interpreter version and allowing
the default pkg-config unavailability error message to be shown.
Fix pkg-config availability check in dnstap/dnstap.m4 and
systemd.m4.
Explicitly set the RD bit for the mesh query flags when prefetching.
These queries have no waiting client but they need to be treated as
recursive.
Fix ip-ratelimit-cookie setting, it was not applied.
Fix to remove unused include from the readzone test program.
Fix unused variable warning in do_cache_remove.
Fix compile warning in worker pthread id printout.
Add unit test skip files and bison and flex output to gitignore.
Fix to use modstack_init in zonemd unit test.
Fix to remove unneeded linebreak in fptr_wlist.c.
Fix compile warnings in fptr_wlist.c.
Fix for repeated use of a DNAME record: first overallocate and then
move the exact size of the init value to avoid false positive heap
overflow reads from address sanitizers.
Fix to print details about the failure to lookup a DNSKEY record
when validation fails due to the missing DNSKEY. Also for key prime
and DS lookups.
Fix for neater printout for error for missing DS response.
Fix neater printout.
Fix #1099: Unbound core dump on SIGSEGV.
Fix for #1099: Fix to check for deleted RRset when the contents
is updated and fetched after it is stored, and also check for a
changed RRset.
Don't check for message TTL changes if the RRsets remain the same.
Fix that validation reason failure that uses string print uses
separate buffer that is passed, from the scratch validation buffer.
Fixup algo_needs_reason string buffer length.
Fix shadowed error string variable in validator dnskey handling.
Update list of known EDE codes.
For #773: In contrib/unbound.service.in set unbound to start after
network-online.target. Also for contrib/unbound_portable.service.in.
Fix #1103: unbound 1.20.0 segmentation fault with nghttp2.
For #1103: fix to also drop mesh state reference when a h2 reply is
dropped.
Add RPZ tag tests in acl_interface.tdir.
For #1102: clearer text for using interface-* options for the
loopback interface.
For #1103: fix to also drop mesh state reference when the discard
limit is reached, when there is an error making a new recursion
state and when the connection is dropped with is_drop.
For #1103: Fix to drop mesh state reference for the http2 stream
associated with the reply, not the currently active stream. And
it does not remove it twice on a mesh_send_reply call. The reply
h2_stream is NULL when not in use, for more initialisation.
Fix dnstap wakeup, a running wakeup timer is left to expire and not
increased, a timer is started when the dtio thread is sleeping,
the timer set disabled when the dtio thread goes to sleep, and
after sleep the thread checks to see if there are messages to log
immediately.
Merge #1110: Make fallthrough explicit for libworker.c.
For #1110: Test for fallthrough attribute in configure and add
fallthrough attribute an...
Unbound 1.20.0
May 8, 2024
This release has a fix for the DNSBomb issue CVE-2024-33655. This has a
low severity for Unbound, since it makes Unbound complicit in targeting
others, but does not affect Unbound so much.
To mitigate the issue new configuration options are introduced.
The options discard-timeout: 1900, wait-limit: 1000
and wait-limit-cookie: 10000 are enabled by default. They limit the
number of outstanding queries that a querier can have. This limits
the reply pulse, and make Unbound less favorable for the issue.
With the config wait-limit-netblock and wait-limit-cookie-netblock
the parameters can be fine tuned for specific destinations.
More information on the attack and Unbound's mitigations are
presented further down.
Other fixes in this release are that Unbound no longer follows symlinks
when truncating the pidfile. Unbound also does not chown the pidfile,
this is for safety reasons. There are also a number of fixes for RPZ, in
handling CNAMEs. There is a memory leak fix for the edns client subnet
cache. For DNSSEC validation a case is fixed when the query is of type
DNAME. The unbound-anchor program is fixed to first write to a temporary
file, before replacing the original. This handles disk full situations,
and because of it unbound-anchor needs permission to create that file,
in the same directory as the original file. There is also a fix for
IP_DONTFRAG, to disable fragmentation instead of the opposite.
The option cache-min-negative-ttl can be used to set the minimum TTL
for negative responses in the cache. It complements existing options to
set the maximum ttl for negative responses and to set the minimum and
maximum ttl but not specifically for negative responses.
The option cachedb-check-when-serve-expired option makes Unbound use
cachedb to check for expired responses, when serve-expired is enabled,
and cachedb is used. It is enabled by default.
The -q option for unbound-checkconf can be added to silence it when
there are no errors.
The DNSBomb vulnerability CVE-2024-33655.
== Summary
The DNSBomb attack, via specially timed DNS queries and answers, can
cause a Denial of Service on resolvers and spoofed targets.
Unbound itself is not vulnerable for DoS, rather it can be used to take
part in a pulsing DoS amplification attack.
Unbound 1.20.0 includes fixes so the impact of the DoS from Unbound
is significantly lower than it used to be and making the attack, and
Unbound's participation, less tempting for attackers.
== Affected products
Unbound up to and including 1.19.3.
== Description
The DNSBomb attack works by sending low-rate spoofed queries for a
malicious zone to Unbound. By controlling the delay of the malicious
authoritative answers, Unbound slowly accumulates pending answers for
the spoofed addresses. When the authoritative answers become available
to Unbound at the same time, Unbound starts serving all the accumulated
queries. This results into large-sized, concentrated response bursts to
the spoofed addresses.
From version 1.20.0 on, Unbound introduces a couple of configuration
options to help mitigate the impact.
Their complete description can be found in the included manpages but
they are also briefly listed here together with their default values for
convenience:
discard-timeout: 1900
After 1900 ms a reply to the client will be dropped.
Unbound would still work on the query but refrain from replying in
order to not accumulate a huge number of "old" replies.
Legitimate clients retry on timeouts.
wait-limit: 1000
wait-limit-cookie: 10000
Limits the amount of client queries that require recursion
(cache-hits are not counted) per IP address. More recursive queries
than the allowed limit are dropped. Clients with a valid EDNS Cookie
can have a different limit, higher by default.
wait-limit: 0 disables all wait limits.
wait-limit-netblock
wait-limit-cookie-netblock
These do not have a default value but they can fine grain
configuration for specific netblocks. With or without EDNS Cookies.
The options above are trying to shrink the DNSBomb window so that the
impact of the DoS from Unbound is significantly lower than it used to be
and making the attack, and Unbound's participation, less tempting for
attackers.
== Acknowledgements
We would like to thank Xiang Li from the Network and Information
Security Lab of Tsinghua University for discovering and disclosing the
attack.
Features
The config for discard-timeout, wait-limit, wait-limit-cookie,
wait-limit-netblock and wait-limit-cookie-netblock was added, for
the fix to the DNSBomb issue.
Merge #1027: Introduce 'cache-min-negative-ttl' option.
Merge #1043 from xiaoxiaoafeifei: Add loongarch support; updates
config.guess(2024-01-01) and config.sub(2024-01-01), verified
with upstream.
Implement cachedb-check-when-serve-expired: yes option, default
is enabled. When serve expired is enabled with cachedb, it first
checks cachedb before serving the expired response.
Fix #876: [FR] can unbound-checkconf be silenced when configuration
is valid?
Bug Fixes
Fix for the DNSBomb vulnerability CVE-2024-33655. Thanks to Xiang Li
from the Network and Information Security Lab of Tsinghua University
for reporting it.
Update doc/unbound.doxygen with 'doxygen -u'. Fixes option
deprecation warnings and updates with newer defaults.
Remove unused portion from iter_dname_ttl unit test.
Fix validator classification of qtype DNAME for positive and
redirection answers, and fix validator signature routine for dealing
with the synthesized CNAME for a DNAME without previously
encountering it and also for when the qtype is DNAME.
Fix qname minimisation for reply with a DNAME for qtype CNAME that
answers it.
Fix doc test so it ignores but outputs unsupported doxygen options.
Fix #1021 Inconsistent Behavior with Changing rpz-cname-override
and doing a unbound-control reload.
Merge #1028: Clearer documentation for tcp-idle-timeout and
edns-tcp-keepalive-timeout.
Fix #1029: rpz trigger clientip and action rpz-passthru not working
as expected.
Fix rpz that the rpz override is taken in case of clientip triggers.
Fix that the clientip passthru action is logged. Fix that the
clientip localdata action is logged. Fix rpz override action cname
for the clientip trigger.
Fix to unify codepath for local alias for rpz cname action override.
Fix rpz for cname override action after nsdname and nsip triggers.
Fix that addrinfo is not kept around but copied and freed, so that
log-destaddr uses a copy of the information, much like NSD does.
Merge #1030: Persist the openssl and expat directories for repeated
Windows builds.
Fix that rpz CNAME content is limited to the max number of cnames.
Fix rpz, it follows iterator CNAMEs for nsip and nsdname and sets
the reply query_info values, that is better for debug logging.
Fix rpz that copies the cname override completely to the temp
region, so there are no references to the rpz region.
Add rpz unit test for nsip action override.
Fix rpz for qtype CNAME after nameserver trigger.
Fix rpz so that rpz CNAME can apply after rpz CNAME. And fix that
clientip and nsip can give a CNAME.
Fix localdata and rpz localdata to match CNAME only if no direct
type match is available.
Merge #831 from Pierre4012: Improve Windows NSIS installer
script (setup.nsi).
For #831: Format text, use exclamation icon and explicit label
names.
Fix name of unit test for subnet cache response.
Fix #1032: The size of subnet_msg_cache calculation mistake cause
memory usage increased beyond expectations.
Fix for #1032, add safeguard to make table space positive.
Fix comment in lruhash space function.
Fix to add unit test for lruhash space that exercises the routines.
Fix that when the server truncates the pidfile, it does not follow
symbolic links.
Fix that the server does not chown the pidfile.
Fix #1034: DoT forward-zone via unbound-control.
Fix for crypto related failures to have a better error string.
Fix #1035: Potential Bug while parsing port from the "stub-host"
string; also affected forward-zones and remote-control host
directives.
Fix #369: dnstap showing extra responses; for client responses
right from the cache when replying with expired data or
prefetching.
Fix #1040: fix heap-buffer-overflow issue in function cfg_mark_ports
of file util/config_file.c.
For #1040: adjust error text and disallow negative ports in other
parts of cfg_mark_ports.
Fix comment syntax for view function views_find_view.
Fix #595: unbound-anchor cannot deal with full disk; it will now
first write out to a temp file before replacing the original one,
like Unbound already does for auto-trust-anchor-file.
Fixup compile without cachedb.
Add test for cachedb serve expired.
Extended test for cachedb serve expired.
Fix makefile dependencies for fake_event.c.
Fix cachedb for serve-expired with serve-expired-reply-ttl.
Fix to not reply serve expired unless enabled for cachedb.
Fix cachedb for serve-expired with serve-expired-client-timeout.
Fixup unit test for cachedb server expired client timeout with
a check if response if from upstream or from cachedb.
Fixup cachedb to not refetch when serve-expired-client-timeout is
used.
Merge #1049 from Petr Men#�k: Py_NoSiteFlag is not needed since
Python 3.8
Fix #1048: Update ax_pkg_swig.m4 and ax_pthread.m4.
Fix configure, autoconf for #1048.
Add checklock feature verbose_locking to trace locks and unlocks.
Fix edns subnet to sort rrset references when storing messages
in the cache. This fixes a race condition in the rrset locks.
Merge #1053: Remove child delegations from cache when grandchild
delegation...
Unbound 1.19.3
Mar 14, 2024
This release has a number of bug fixes. The CNAME synthesized for a
DNAME record uses the original TTL, of the DNAME record, and that means
it can be cached for the TTL, instead of 0.
There is a fix that when a message was stored in cache, but one of the
RRsets was not updated due to cache policy, it now restricts the message
TTL if the cache version of the RRset has a shorter TTL. It avoids a
bug where the message is not expired, but its contents is expired.
For dnstap, it logs type DoH and DoT correctly, if that is used for
the message.
The b.root-servers.net address is updated in the default root hints.
When performing retries for failed sends, a retry at a smaller UDP size
is now not performed when that attempt is not actually smaller, and at
defaults, since the flag day changes, it is the same size. This makes
it skip the step, it is useless because there is no reduction in size.
Clients with a valid DNS Cookie will bypass the ratelimit, if one is
set. The value from ip-ratelimit-cookie is used for these queries.
Furthermore there is a fix to make correct EDE Prohibited answers for
access control denials, and a fix for EDNS client subnet scope zero
answers.
Features:
Merge PR #973: Use the origin (DNAME) TTL for synthesized CNAMEs as
per RFC 6672.
Bug Fixes:
Fix unit test parse of origin syntax.
Use 127.0.0.1 explicitly in tests to avoid delays and errors on
newer systems.
Fix #964: config.h.in~ backup file in release tar balls.
Merge #968: Replace the obsolescent fgrep with grep -F in tests.
Merge #971: fix 'WARNING: Message has 41 extra bytes at end'.
Fix #969: [FR] distinguish Do53, DoT and DoH in the logs.
Fix dnstap that assertion failed on logging other than UDP and TCP
traffic. It lists it as TCP traffic.
Fix to sync the tests script file common.sh.
iana portlist update.
Updated IPv4 and IPv6 address for b.root-servers.net in root hints.
Update test script file common.sh.
Fix tests to use new common.sh functions, wait_logfile and
kill_from_pidfile.
Fix #974: doc: default number of outgoing ports without libevent.
Merge #975: Fixed some syntax errors in rpl files.
Fix root_zonemd unit test, it checks that the root ZONEMD verifies,
now that the root has a valid ZONEMD.
Update example.conf with cookie options.
Merge #980: DoH: reject non-h2 early. To fix #979: Improve errors
for non-HTTP/2 DoH clients.
Merge #985: Add DoH and DoT to dnstap message.
Fix #983: Sha1 runtime insecure change was incomplete.
Remove unneeded newlines and improve indentation in remote control
code.
Merge #987: skip edns frag retry if advertised udp payload size is
not smaller.
Fix unit test for #987 change in udp1xxx retry packet send.
Merge #988: Fix #981: dump_cache truncates large records.
Fix to link with -lcrypt32 for OpenSSL 3.2.0 on Windows.
Fix to link with libssp for libcrypto and getaddrinfo check for
only header. Also update crosscompile to remove ssp for 32bit.
Merge #993: Update b.root-servers.net also in example config file.
Update workflow for ports to use newer openssl on windows compile.
Fix warning for windres on resource files due to redefinition.
Fix for #997: Print details for SSL certificate failure.
Update error printout for duplicate trust anchors to include the
trust anchor name (relates to #920).
Update message TTL when using cached RRSETs. It could result in
non-expired messages with expired RRSETs (non-usable messages by
Unbound).
Merge #999: Search for protobuf-c with pkg-config.
Fix #1006: Can't find protobuf-c package since #999.
Fix documentation for access-control in the unbound.conf man page.
Merge #1010: Mention REFUSED has the TC bit set with unmatched
allow_cookie acl in the manpage. It also fixes the code to match the
documentation about clients with a valid cookie that bypass the
ratelimit regardless of the allow_cookie acl.
Document the suspend argument for process_ds_response().
Move github workflows to use checkoutv4.
Fix edns subnet replies for scope zero answers to not get stored
in the global cache, and in cachedb, when the upstream replies
without an EDNS record.
Fix for #1022: Fix ede prohibited in access control refused answers.
Fix unbound-control-setup.cmd to use 3072 bits so that certificates
are long enough for newer OpenSSL versions.
Fix TTL of synthesized CNAME when a DNAME is used from cache.
Fix unbound-control-setup.cmd to have CA v3 basicConstraints,
like unbound-control-setup.sh has.
Unbound 1.19.2
Mar 7, 2024
This security release fixes CVE-2024-1931.
NLnet Labs Unbound version 1.18.0 up to and including version 1.19.1
contain a vulnerability that can cause denial of service by a certain
code path that can lead to an infinite loop.
Unbound 1.18.0 introduced a feature that removes EDE records from
responses with size higher than the client's advertised buffer size.
Before removing all the EDE records however, it would try to see if
trimming the extra text fields on those records would result in an
acceptable size while still retaining the EDE codes.
Due to an unchecked condition, the code that trims the text of the EDE
records could loop indefinitely.
This happens when Unbound would reply with attached EDE information on a
positive reply and the client's buffer size is smaller than the needed
space to include EDE records.
The vulnerability can only be triggered when the 'ede: yes' option is
used; non default configuration.
From version 1.19.2 on, the code is fixed to avoid looping indefinitely.
We would like to thank Fredrik Pettai and Patrik Lundin from SUNET for
notifying us about the issue and working with us to identify the
vulnerability.
Bug Fixes:
Fix CVE-2024-1931, Denial of service when trimming EDE text on
positive replies.
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