CVE-2020-8624: update-policy rules of type "subdomain" are enforced incorrectly
Document version: 2.0
Posting date: 20 August 2020
Program impacted: BIND
Versions affected: BIND 9.9.12 -> 9.9.13, 9.10.7 -> 9.10.8, 9.11.3 -> 9.11.21, 9.12.1 -> 9.16.5, 9.17.0 -> 9.17.3, also affects 9.9.12-S1 -> 9.9.13-S1, 9.11.3-S1 -> 9.11.21-S1 of the BIND 9 Supported Preview Edition
Change 4885 inadvertently caused "update-policy" rules of type "subdomain" to be treated as if they were of type "zonesub", allowing updates to all parts of the zone along with the intended subdomain.
An attacker who has been granted privileges to change a specific subset of the zone's content could abuse these unintended additional privileges to update other contents of the zone.
CVSS Score: 3.9
CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N/E:P/RL:O/RC:C
For more information on the Common Vulnerability Scoring System and to obtain your specific environmental score please visit: https://nvd.nist.gov/vuln-metrics/cvss/v3-calculator?vector=AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N/E:P/RL:O/RC:C&version=3.1.
No workarounds known.
We are not aware of any active exploits but the issue has been described on a public bug tracker for a Linux distribution.
Upgrade to the patched release most closely related to your current version of BIND:
- BIND 9.11.22
- BIND 9.16.6
- BIND 9.17.4
BIND Supported Preview Edition is a special feature preview branch of BIND provided to eligible ISC support customers.
- BIND 9.11.22-S1
Acknowledgments: ISC would like to thank Joop Boonen of credativ GmbH for bringing this vulnerability to our attention.
Document revision history:
1.0 Early Notification, 12 August 2020
1.1 Updated Posting Date, 17 August 2020
2.0 Public Announcement, 20 August 2020
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 firstname.lastname@example.org. To report a new issue, please encrypt your message using email@example.com'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 https://kb.isc.org/docs/aa-00861.
The Knowledgebase article https://kb.isc.org/docs/cve-2020-8624 is the complete and official security advisory document.
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.