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F5 Networks BIG-IP : BIND vulnerability (K000162286)

high Nessus Plugin ID 330803

Synopsis

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

Description

The version of F5 Networks BIG-IP installed on the remote host is prior to 21.1.0. It is, therefore, affected by a vulnerability as referenced in the K000162286 advisory.

 If a BIND resolver is performing DNSSEC validation and encounters a maliciously crafted zone, the resolver may consume excessive CPU. Authoritative-only servers are generally unaffected, although there are circumstances where authoritative servers may make recursive queries (see: https://kb.isc.org/docs/why- does-my-authoritative-server-make-recursive-queries). This issue affects BIND 9 versions 9.11.0 through 9.16.50, 9.18.0 through 9.18.46, 9.20.0 through 9.20.20, 9.21.0 through 9.21.19, 9.11.3-S1 through 9.16.50-S1, 9.18.11-S1 through 9.18.46-S1, and 9.20.9-S1 through 9.20.20-S1.(CVE-2026-1519)BIG-IP LTM with no DNS provisionedThe BIG-IP system contains the vulnerable version of BIND, and BIND is enabled by default. However, when LTM is provisioned and DNS is not provisioned, BIND is present but is not used as a resolver performing Domain Name System Security Extensions (DNSSEC) validation. Because the attack requires DNSSEC validation to be in the processing path, LTM with no DNS module provisioned is not vulnerable.BIG-IP with DNS provisionedBIG-IP DNS is vulnerable under the following conditions:BIND is acting as a recursive resolver. By default, BIND on the BIG-IP system hasrecursion no;configured, which means it is not a recursive resolver. If you have manually enabled recursion by addingrecursion yes;to thenamed.conffile, BIND can perform DNSSEC validation on behalf of clients and is therefore vulnerable.
 You can check this by runninggrep recursion /var/named/config/named.conf. If the result showsrecursion no;, this configuration is not vulnerable.DNS Cache is configured as a Validating Resolver. If a DNS Cache instance has been configured with the type set to Validating Resolver, it performs DNSSEC validation as its core function regardless of what BIND's recursion setting is. This means a system can be vulnerable through this path even if BIND recursion is disabled. You can check this by running thetmsh list ltm dns cache validating-resolvercommand. If any output is returned, a Validating Resolver cache exists and the system is vulnerable when using this configuration.A plain Resolver cache type (not Validating Resolver) performs recursive resolution but does not perform DNSSEC validation, so it is not directly vulnerable to this specific CVE.Even if BIND recursion is disabled, if the system relies on BIND's DNSSEC validation logic and can accept queries from sources that could reach attacker-controlled domains, there is still potential exposure. In practice, the Validating Resolver DNS Cache path is the most likely way this applies when BIND recursion is off.

Tenable has extracted the preceding description block directly from the F5 Networks BIG-IP security advisory.

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

Solution

Upgrade to one of the non-vulnerable versions listed in the F5 Solution K000162286.

See Also

https://my.f5.com/manage/s/article/K000162286

Plugin Details

Severity: High

ID: 330803

File Name: f5_bigip_SOL000162286.nasl

Version: 1.1

Type: Local

Published: 7/29/2026

Updated: 7/29/2026

Configuration: Enable paranoid mode

Supported Sensors: Nessus

Risk Information

VPR

Risk Factor: Low

Score: 3

Percentile: 23.73

CVSS v2

Risk Factor: High

Base Score: 7.8

Temporal Score: 5.8

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

CVSS Score Source: CVE-2026-1519

CVSS v3

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, Host/BIG-IP/hotfix, Host/BIG-IP/modules, Host/BIG-IP/version, Settings/ParanoidReport

Exploit Ease: No known exploits are available

Patch Publication Date: 7/29/2026

Vulnerability Publication Date: 3/25/2026

Reference Information

CVE: CVE-2026-1519