CVE-2019-6467: An error in the nxdomain redirect feature can cause BIND to exit with an INSIST assertion failure in query.c

CVE: CVE-2019-6467

Document version: 2.0

Posting date: 24 April 2019

Program impacted: BIND

Versions affected: BIND 9.12.0-> 9.12.4, 9.14.0. Also affects all releases in the 9.13 development branch.

Severity: Medium

Exploitable: Remotely

Description:

A programming error in the nxdomain-redirect feature can cause an assertion failure in query.c if the alternate namespace used by nxdomain-redirect is a descendant of a zone that is served locally.

The most likely scenario where this might occur is if the server, in addition to performing NXDOMAIN redirection for recursive clients, is also serving a local copy of the root zone or using mirroring to provide the root zone, although other configurations are also possible.

Impact:

An attacker who can deliberately trigger the condition on a server with a vulnerable configuration can cause BIND to exit, denying service to other clients.

CVSS Score: 5.9

CVSS Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

For more information on the Common Vulnerability Scoring System and to obtain your specific environmental score please visit: https://www.first.org/cvss/calculator/3.0#CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H.

Workarounds:

Exploitation of this defect can be effectively prevented by disabling the nxdomain-redirect feature in the nameserver's configuration.

Active exploits:

None known.

Solution:

Upgrade to the patched release most closely related to your current version of BIND:

• BIND 9.12.4-P1
• BIND 9.14.1

Document revision history:

1.0 Early Notification, 15 April 2019
1.1 Removed BIND 9.11.6-P1 from Solution version list
2.0 Public Disclosure, 24 April 2019

Related documents:

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

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Note:

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/downloads/.)

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.

This Knowledgebase article is the complete and official security advisory document.

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