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CVE-2021-25215

An assertion check can fail while answering queries for DNAME records that require the DNAME to be processed to resolve itself

CVSS 7.5 HIGHEPSS 11.3%
In short

A bug in BIND DNS software causes the server to crash when processing certain DNS queries for DNAME records. An attacker can send a specially crafted query to make the DNS service stop working.

Technical detail

The vulnerability exists in BIND's DNAME record processing logic where a failed assertion check causes the named process to terminate. An unauthenticated attacker can trigger a denial of service by sending a query for a DNAME record that requires recursive processing, affecting BIND versions 9.0.0 through 9.17.11 across multiple branches.

Summary generated and translated by AI from the official description.
In BIND 9.0.0 -> 9.11.29, 9.12.0 -> 9.16.13, and versions BIND 9.9.3-S1 -> 9.11.29-S1 and 9.16.8-S1 -> 9.16.13-S1 of BIND Supported Preview Edition, as well as release versions 9.17.0 -> 9.17.11 of the BIND 9.17 development branch, when a vulnerable version of named receives a query for a record triggering the flaw described above, the named process will terminate due to a failed assertion check. The vulnerability affects all currently maintained BIND 9 branches (9.11, 9.11-S, 9.16, 9.16-S, 9.17) as well as all other versions of BIND 9.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Affected products
ISC · BIND9

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References
https://cert-portal.siemens.com/productcert/pdf/ssa-389290.pdfhttps://kb.isc.org/v1/docs/cve-2021-25215https://lists.debian.org/debian-lts-announce/2021/05/msg00001.htmlhttps://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/VEC2XG4Q2ODTN2C4CGXEIXU3EUTBMK7L/https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/ZDSRPCJQ7MZC6CENH5PO3VQOFI7VSWBE/https://security.netapp.com/advisory/ntap-20210521-0006/https://www.debian.org/security/2021/dsa-4909https://www.oracle.com/security-alerts/cpuoct2021.htmlhttp://www.openwall.com/lists/oss-security/2021/04/29/1http://www.openwall.com/lists/oss-security/2021/04/29/2http://www.openwall.com/lists/oss-security/2021/04/29/3http://www.openwall.com/lists/oss-security/2021/04/29/4