ISC BIND DNAME Recursion DoS (CVE-2021-25215)

high Nessus Plugin ID 149211


The remote name server is affected by a denial of service vulnerability.


According to its self-reported version, the ISC Bind present on the remote host is affected by a denial of service vulnerability:

- DNAME records, described in RFC 6672, provide a way to redirect a subtree of the domain name tree in the DNS. A flaw in the way named processes these records may trigger an attempt to add the same RRset to the ANSWER section more than once. When a vulnerable version of named receives a query for a record triggering the flaw, the named process will terminate due to a failed assertion check.

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.


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

See Also

Plugin Details

Severity: High

ID: 149211

File Name: bind9_91712_cve-2021-25215.nasl

Version: 1.4

Type: remote

Family: DNS

Published: 4/30/2021

Updated: 11/9/2021

Configuration: Enable paranoid mode

Supported Sensors: Nessus

Risk Information


Risk Factor: Low

Score: 3.6


Risk Factor: Medium

Base Score: 5

Temporal Score: 3.7

Vector: CVSS2#AV:N/AC:L/Au:N/C:N/I:N/A:P

CVSS Score Source: CVE-2021-25215


Risk Factor: High

Base Score: 7.5

Temporal Score: 6.5

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

Temporal Vector: CVSS:3.0/E:U/RL:O/RC:C

Vulnerability Information

CPE: cpe:/a:isc:bind

Required KB Items: Settings/ParanoidReport, bind/version

Exploit Ease: No known exploits are available

Patch Publication Date: 4/28/2021

Vulnerability Publication Date: 4/28/2021

Reference Information

CVE: CVE-2021-25215

IAVA: 2021-A-0206-S