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F5 Networks BIG-IP : NLnet Labs Unbound vulnerability (K000162178)

high Nessus Plugin ID 327467

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 tested version. It is, therefore, affected by a vulnerability as referenced in the K000162178 advisory.

 NLnet Labs Unbound 1.16.2 up to and including version 1.25.0 has a vulnerability of the 'ghost domain names' family of attacks that could extend the ghost domain window by up to one cached TTL configured value. Similar to other 'ghost domain names' attacks, an adversary needs to control a (ghost) zone and be able to query a vulnerable Unbound. A single client NS query can cause Unbound to overwrite the cached expired parent-side referral NS rrset with the child-side apex NS rrset and essentially extend the ghost domain window by up to one cached TTL configured value ('cache-max-ttl'). In configurations where 'harden- referral-path: yes' is used (non-default configuration), no client NS query is required since Unbound implicitly performs that query. Unbound 1.25.1 contains a patch with a fix that does not allow extension of TTLs for (parent) NS records regardless of their trust.(CVE-2026-40622)

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

The vendor has acknowledged the vulnerability, but no solution has been provided.
Refer to the vendor for remediation guidance.

See Also

https://my.f5.com/manage/s/article/K000162178

Plugin Details

Severity: High

ID: 327467

File Name: f5_bigip_SOL000162178.nasl

Version: 1.1

Type: Local

Published: 7/16/2026

Updated: 7/16/2026

Configuration: Enable paranoid mode

Supported Sensors: Nessus

Risk Information

VPR

Risk Factor: Low

Score: 3

Percentile: 23.76

CVSS v2

Risk Factor: High

Base Score: 7.8

Temporal Score: 5.8

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

CVSS Score Source: CVE-2026-40622

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:H/A:N

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

CVSS v4

Risk Factor: High

Base Score: 8.7

Threat Score: 6.6

Threat Vector: CVSS:4.0/E:U

Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N

Vulnerability Information

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

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

Vulnerability Publication Date: 5/20/2026

Reference Information

CVE: CVE-2026-40622