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Fencer Vulns
high 7.5

CVE-2026-40622 json

Another 'ghost domain names' attack variant

published 2026-05-20 5 mo ago modified 2026-07-24 3 mo ago also EUVD-2026-31080

cvss
7.5
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
0.1%
EPSS 0.1% chance of exploitation in 30 days, percentile 3%
public exploits
0
none known

Summary

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.

Patch / fix

  • NLnet Labs Unbound 1.25.1
  • unbound Debian 13 1.26.1-0+deb13u1
  • unbound Debian 14 1.25.2-1

debian advisories DEBIAN-CVE-2026-40622

  • unbound Ubuntu 24.04 LTS 1.19.2-1ubuntu3.8
  • unbound Ubuntu 25.10 1.22.0-2ubuntu2.3
  • unbound Ubuntu 26.04 LTS 1.24.2-1ubuntu2.1

ubuntu advisories UBUNTU-CVE-2026-40622

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • unbound RHEL 8 1.16.2-5.12.el8_10
  • unbound-libs RHEL 8 1.16.2-5.12.el8_10
  • python3-unbound RHEL 8 1.16.2-5.12.el8_10
  • unbound RHEL 9 1.24.2-3.el9_8.2
  • unbound-libs RHEL 9 1.24.2-3.el9_8.2
  • unbound-dracut RHEL 9 1.24.2-3.el9_8.2
  • python3-unbound RHEL 9 1.24.2-3.el9_8.2
  • unbound RHEL 10.2 1.24.2-7.el10_2.2

red hat advisories RHSA-2026:37282RHSA-2026:36777RHSA-2026:36320RHSA-2026:20357

  • unbound SLES for SAP 15 SP6, SLES 15 SP6-LTSS, SLE Module for Package Hub 15 SP7 +1 more 1.25.2-150600.23.19.1
  • unbound Linux Micro 6.0 1.25.2-1.1
  • unbound Linux Micro 6.1 1.25.2-slfo.1.1_1.1
  • unbound SLES 16.0, Linux Micro 6.2, SLES for SAP applications 16.0 1.25.2-160000.1.1
  • unbound SLES 16.0, Linux Micro 6.2, SLES for SAP applications 16.0 1.24.1-160000.2.1
  • unbound SLES for SAP 15 SP5, SLES for SAP 15 SP4, SLES 15 SP5-LTSS +6 more 1.20.0-150100.10.25.1

suse advisories SUSE-SU-2026:3885-1SUSE-SU-2026:23360-1SUSE-SU-2026:23349-1SUSE-SU-2026:23050-1SUSE-SU-2026:23215-1SUSE-SU-2026:23226-1

  • unbound openSUSE Leap 16.0 1.25.2-160000.1.1
  • unbound openSUSE Leap 16.0 1.24.1-160000.2.1
  • unbound openSUSE Tumbleweed 1.25.1-1.1

opensuse advisories openSUSE-SU-2026:21550-1openSUSE-SU-2026:21083-1openSUSE-SU-2026:10903-1

  • unbound AlmaLinux 8 1.16.2-5.12.el8_10
  • unbound-libs AlmaLinux 8 1.16.2-5.12.el8_10
  • python3-unbound AlmaLinux 8 1.16.2-5.12.el8_10
  • unbound AlmaLinux 9 1.24.2-3.el9_8.2
  • unbound-libs AlmaLinux 9 1.24.2-3.el9_8.2
  • unbound-dracut AlmaLinux 9 1.24.2-3.el9_8.2
  • python3-unbound AlmaLinux 9 1.24.2-3.el9_8.2
  • unbound AlmaLinux 10 1.24.2-7.el10_2.2

almalinux advisories ALSA-2026:37282ALSA-2026:36777ALSA-2026:36320

  • unbound Rocky Linux 10 1.24.2-7.el10_2.2
  • unbound Rocky Linux 9 1.24.2-3.el9_8.2
  • unbound Rocky Linux 8 1.16.2-5.12.el8_10

rocky linux advisories RLSA-2026:36320RLSA-2026:36777RLSA-2026:37282

  • unbound Alpine 3.23, Alpine 3.22 1.25.2-r0
  • unbound Alpine 3.24 1.25.1-r0

alpine advisories ALPINE-CVE-2026-40622

Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • unbound Azure Linux 3.0 1.25.1-1

azure linux advisories AZL-87035

Azure Linux vulnerability data, Copyright (c) Microsoft Corporation, from https://github.com/microsoft/AzureLinuxVulnerabilityData via OSV, under the MIT licence; changed: normalised to fixed package versions per release. MIT

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-40622 updated cvss 7.5

unbound: Unbound: Cache manipulation via 'ghost domain names' attack

  • Red Hat Enterprise Linux 6 unbound, unbound-libs, unbound-python
    affected: no fix planned “Out of support scope”
  • Red Hat Enterprise Linux 7 unbound, unbound-libs, unbound-python Red Hat OpenShift Container Platform 4 openshift/ose-rhel-coreos-8 Red Hat OpenShift Container Platform 5 openshift/ose-rhel-coreos-9
    affected: no fix available
  • Red Hat Enterprise Linux AppStream (v. 8) unbound 1.16.2-5.12.el8_10, unbound-libs 1.16.2-5.12.el8_10, python3-unbound 1.16.2-5.12.el8_10
    fixed: vendor fix RHSA-2026:37282
  • Red Hat Enterprise Linux AppStream (v. 9) unbound 1.24.2-3.el9_8.2, unbound-libs 1.24.2-3.el9_8.2, unbound-dracut 1.24.2-3.el9_8.2, python3-unbound 1.24.2-3.el9_8.2
    fixed: vendor fix RHSA-2026:36777
  • Red Hat Enterprise Linux AppStream (v. 10) unbound 1.24.2-7.el10_2.2, unbound-libs 1.24.2-7.el10_2.2, unbound-utils 1.24.2-7.el10_2.2, unbound-anchor 1.24.2-7.el10_2.2, unbound-dracut 1.24.2-7.el10_2.2, python3-unbound 1.24.2-7.el10_2.2
    fixed: vendor fix RHSA-2026:36320
  • Red Hat Enterprise Linux CodeReady Linux Builder (v. 9) unbound-devel 1.24.2-3.el9_8.2, unbound-debuginfo 1.24.2-3.el9_8.2, unbound-debugsource 1.24.2-3.el9_8.2, unbound-libs-debuginfo 1.24.2-3.el9_8.2, python3-unbound-debuginfo 1.24.2-3.el9_8.2
    fixed: vendor fix RHSA-2026:36777
  • Red Hat Enterprise Linux CodeReady Linux Builder (v. 10) unbound-devel 1.24.2-7.el10_2.2, unbound-debuginfo 1.24.2-7.el10_2.2, unbound-debugsource 1.24.2-7.el10_2.2, unbound-libs-debuginfo 1.24.2-7.el10_2.2, unbound-utils-debuginfo 1.24.2-7.el10_2.2, unbound-anchor-debuginfo 1.24.2-7.el10_2.2, +1 more
    fixed: vendor fix RHSA-2026:36320
  • Red Hat Hardened Images unbound 1.25.1-1.hum1, unbound-libs 1.25.1-1.hum1, unbound-munin 1.25.1-1.hum1, unbound-utils 1.25.1-1.hum1, unbound-anchor 1.25.1-1.hum1, unbound-dracut 1.25.1-1.hum1, +1 more
    fixed: vendor fix RHSA-2026:20357
show 1 more
  • Red Hat OpenShift Container Platform 4.22 rhcos 4.22.9.8.202608130832
    fixed: vendor fix RHSA-2026:54769

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
yes
Technical impact
partial
Assessed
5 mo ago

Exploit prediction

0.14% chance of exploitation in the next 30 days, higher than 3% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 4.0 6.6 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/E:U/U:Amber
CNA 4.0 6.6 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/E:U/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:Amber
NVD 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

Affected products

  • NLnet Labs Unbound

Classification

Weakness

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.