CVE-2020-8620: A specially crafted large TCP payload can trigger an assertion failure in tcpdns.c
Document version: 2.0
Posting date: 20 August 2020
Program impacted: BIND
Versions affected: BIND 9.15.6 -> 9.16.5, 9.17.0 -> 9.17.3
In versions of BIND that use the libuv network manager (9.16.x is the only stable branch affected) an incorrectly specified maximum buffer size allows a specially crafted large TCP payload to trigger an assertion failure when it is received.
An attacker who can establish a TCP connection with the server and send data on that connection can exploit this to trigger the assertion failure, causing the server to exit.
CVSS Score: 6.7
CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/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:N/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 9.16.6
- BIND 9.17.4
Acknowledgments: ISC would like to thank Emanuel Almeida of Cisco Systems, Inc. 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-2020-8620 is the complete and official security advisory document.
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