Bug 1197137 - (CVE-2022-0635) VUL-0: CVE-2022-0635: bind: RFC 8198 Aggressive Use of DNSSEC-Validated Cache feature
VUL-0: CVE-2022-0635: bind: RFC 8198 Aggressive Use of DNSSEC-Validated Cache...
Classification: Novell Products
Product: SUSE Security Incidents
Classification: Novell Products
Component: Incidents
Other Other
: P3 - Medium : Normal
: ---
Assigned To: Security Team bot
Security Team bot
Depends on:
  Show dependency treegraph
Reported: 2022-03-15 14:04 UTC by Alexander Bergmann
Modified: 2022-03-29 12:25 UTC (History)
2 users (show)

See Also:
Found By: ---
Services Priority:
Business Priority:
Blocker: ---
Marketing QA Status: ---
IT Deployment: ---


Note You need to log in before you can comment on or make changes to this bug.
Description Alexander Bergmann 2022-03-15 14:04:52 UTC
Via distros:

Date: Tue, 15 Mar 2022 13:38:28 +0000
From: ISC Security Officer <security-officer@isc.org>

CVE: CVE-2022-0635

Document version: 1.0

Posting date: 16 March 2022

Program impacted: BIND

Versions affected: BIND 9.18.0

Severity: High

Exploitable: Remotely


We refactored the RFC 8198 Aggressive Use of DNSSEC-Validated Cache
feature (synth-from-dnssec) for the new BIND 9.18.0 stable release, and
changed the default so that is now automatically enabled for
dnssec-validating resolvers. Subsequently it was found that repeated
patterns of specific queries to servers with this feature enabled could
cause an INSIST failure in query.c:query_dname which causes named to
terminate unexpectedly.

The vulnerability affects BIND resolvers running 9.18.0 that have both
dnssec-validation and synth-from-dnssec enabled. (Note that
dnssec-validation auto; is the default setting unless configured otherwise
in named.conf and that enabling dnssec-validation automatically enables
synth-from-dnssec unless explicitly disabled)


When a vulnerable version of named receives a series of specific queries,
the named process will eventually terminate due to a failed assertion

CVSS Score: 7.0


For more information on the Common Vulnerability Scoring System and to
obtain your specific environmental score please visit:


The failure can be avoided by adding this option to named.conf:

synth-from-dnssec no;


However we do not recommend disabling this feature other than as a
temporary workaround because it provides protection from
pseudo-random-subdomain attacks against DNSSEC-signed zones.

Active exploits:

We are not aware of any active exploits.


     Users of BIND 9.18.0 should upgrade to BIND 9.18.1

ISC would like to thank Vincent Levigneron of AFNIC for reporting this
issue to us and for verifying the fix and workaround.

Document revision history:

1.0 Early Notification, 9 March 2022

Related documents:

See Operational Notification: synth-from-dnssec may cause slow resolution
on resolvers under certain cache conditions for more information regarding
early BIND support for RFC 8198 Aggressive Use of DNSSEC-Validated Cache
and our recommendation that this feature be disabled until versions of
BIND were made available which contain an improvement to the
synth-from-dnssec feature.

See our BIND 9 Security Vulnerability Matrix for a complete listing of
security vulnerabilities and versions affected.

Do you still have questions? Questions regarding this advisory should go
to security-officer@isc.org. To report a new issue, please encrypt your
message using security-officer@isc.org's PGP key which can be found here:
https://www.isc.org/pgpkey/. If you are unable to use encrypted email, you
may also report new issues at: https://www.isc.org/reportbug/.


ISC patches only currently supported versions. When possible we indicate
EOL versions affected. (For current information on which versions are
actively supported, please see https://www.isc.org/download/.)

ISC Security Vulnerability Disclosure Policy:

Details of our current security advisory policy and practice can be found
in the ISC Software Defect and Security Vulnerability Disclosure Policy at

The Knowledgebase article https://kb.isc.org/docs/cve-2022-0635 is the
complete and official security advisory document.

Legal Disclaimer:

Internet Systems Consortium (ISC) is providing this notice on an "AS IS"
basis. No warranty or guarantee of any kind is expressed in this notice
and none should be implied. ISC expressly excludes and disclaims any
warranties regarding this notice or materials referred to in this notice,
including, without limitation, any implied warranty of merchantability,
fitness for a particular purpose, absence of hidden defects, or of
non-infringement. Your use or reliance on this notice or materials
referred to in this notice is at your own risk. ISC may change this notice
at any time. A stand-alone copy or paraphrase of the text of this document
that omits the document URL is an uncontrolled copy. Uncontrolled copies
may lack important information, be out of date, or contain factual errors.
Comment 2 Alexander Bergmann 2022-03-15 15:35:19 UTC
Created attachment 857003 [details]
Comment 3 Gianluca Gabrielli 2022-03-17 07:56:00 UTC
Public: https://kb.isc.org/docs/cve-2022-0635
Comment 4 Josef Möllers 2022-03-22 08:07:02 UTC
This bug applies only to factory, fixed with upgrade to 9.18.1:
Comment 5 Gianluca Gabrielli 2022-03-29 12:25:50 UTC