CVE-2020-8622: A truncated TSIG response can lead to an assertion failure
Document version: 2.0
Posting date: 20 August 2020
Program impacted: BIND
Versions affected: BIND 9.0.0 -> 9.11.21, 9.12.0 -> 9.16.5, 9.17.0 -> 9.17.3, also affects 9.9.3-S1 -> 9.11.21-S1 of the BIND 9 Supported Preview Edition
Attempting to verify a truncated response to a TSIG-signed request leads to an assertion failure.
An attacker on the network path for a TSIG-signed request, or operating the server receiving the TSIG-signed request, could send a truncated response to that request, triggering an assertion failure, causing the server to exit.
Alternately, an off-path attacker would have to correctly guess when a TSIG-signed request was sent, along with other characteristics of the packet and message, and spoof a truncated response to trigger an assertion failure, causing the server to exit.
CVSS Score: 5.9
CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H/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:N/A:H/E:P/RL:O/RC:C&version=3.1.
No workarounds known.
We are not aware of any active exploits.
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 Dave Feldman, Jeff Warren, and Joel Cunningham of Oracle 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.
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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-2020-8622 is the complete and official security advisory document.
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