F5 Networks BIG-IP : Unbound DNS Cache vulnerabilities (K37661551)

high Nessus Plugin ID 138233


The remote device is missing a vendor-supplied security patch.



Unbound before 1.10.1 has Insufficient Control of Network Message Volume, aka an 'NXNSAttack' issue. This is triggered by random subdomains in the NSDNAME in NS records.

CVE-2020-12663 Unbound before 1.10.1 has an infinite loop via malformed DNS answers received from upstream servers.


There are three types of DNS cache configurations available on the BIG-IP system: a transparent cache, a resolver cache, and a validating resolver cache. Only BIG-IP systems licensed for DNS services and using the DNS Cache feature are vulnerable.

Notes :

The DNS Cache feature is available only when you licensethe BIG-IP systemfor DNS Services, but you do NOT have to provisionthe BIG-IP GTM or BIG-IP DNS moduleon your BIG-IP system.

Starting with BIG-IP 12.0.0, F5 renamed BIG-IP GTM to BIG-IP DNS.

DNS Express does not use Unbound and is not vulnerable to either CVE-2020-12662 or CVE-2020-12663.


When the DNS Cache feature is enabled on the BIG-IP system, an attacker may exploit this vulnerability to generate a large number of communications between the BIG-IP system and the victim's authoritative DNS server to cause a denial-of-service (DoS) attack.

Note : For more information about NXNSAttack, refer to the NXNSAttack research paper.


A remote attacker may be able to perform a DoS attack on a DNS cache configured on the BIG-IP system by causing Unbound to become unresponsive.


Upgrade to one of the non-vulnerable versions listed in the F5 Solution K37661551.

See Also


Plugin Details

Severity: High

ID: 138233

File Name: f5_bigip_SOL37661551.nasl

Version: 1.8

Type: local

Published: 7/9/2020

Updated: 11/3/2023

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-2020-12663


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:f5:big-ip_domain_name_system, cpe:/a:f5:big-ip_global_traffic_manager, cpe:/h:f5:big-ip

Required KB Items: Host/local_checks_enabled, Settings/ParanoidReport, Host/BIG-IP/hotfix, Host/BIG-IP/modules, Host/BIG-IP/version

Exploit Ease: No known exploits are available

Patch Publication Date: 6/3/2020

Vulnerability Publication Date: 5/19/2020

Reference Information

CVE: CVE-2020-12662, CVE-2020-12663