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Fencer Intel
high 7.5

CVE-2026-44390 json

Unbounded name compression in certain cases causes degradation of service

published 5mo ago modified 2mo ago also EUVD-2026-31088

cvss
7.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.6%
EPSS 0.6% chance of exploitation in 30 days, percentile 51%
public exploits
0
none known

Summary

NLnet Labs Unbound up to and including version 1.25.0 has a vulnerability when handling replies with very large RRsets that Unbound needs to perform name compression for. Malicious upstream responses with very large RRsets with records that don't share a suffix above the root can cause Unbound to spend a considerable time applying name compression to downstream replies. This can lead to degraded performance and eventually denial of service in well orchestrated attacks. An adversary can exploit the vulnerability by querying Unbound for the specially crafted contents of a malicious zone with very large RRsets. Before Unbound replies to the query it will try to apply name compression which was an unbounded operation that could lock the CPU until the whole packet was complete. A compression limit was introduced in 1.21.1 for this but it didn't account for the case where records would not share any suffix above the root. That causes Unbound to go in a different code path because of the compression tree lookup failure and eventually not increment the compression counter for those operations. Unbound 1.25.1 contains a patch with a fix that increments the compression counter regardless of the compression tree lookup. This is a complement fix to CVE-2024-8508.

Patch / fix

  • NLnet Labs Unbound 1.25.1
  • Red Hat Red Hat Enterprise Linux 10 0:1.24.2-7.el10_2.2
  • Red Hat Red Hat Enterprise Linux 8 0:1.16.2-5.12.el8_10
  • Red Hat Red Hat Enterprise Linux 9 0:1.24.2-3.el9_8.2
  • Red Hat Red Hat Hardened Images 1.25.1-2.hum1
  • unbound Debian 13 1.22.0-2+deb13u3
  • unbound Debian 14 1.25.1-1

debian advisories DEBIAN-CVE-2026-44390

  • unbound Ubuntu 22.04 LTS 1.13.1-1ubuntu5.15
  • 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-2026-44390

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-2026:24013

  • 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-2026:22160-1SUSE-SU-2026:22213-1SUSE-SU-2026:2369-1

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

opensuse advisories openSUSE-SU-2026:21083-1openSUSE-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-2026-44390

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-87045

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

Is CVE-2026-44390 in your stack? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

Check with Fencer

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-2026-44390 updated cvss 7.5

unbound: Unbound: Denial of Service due to excessive resource consumption with large DNS Resource Record Sets

  • Red Hat Enterprise Linux 6 unbound, unbound-libs, unbound-python Red Hat Enterprise Linux 7 unbound, unbound-libs, unbound-python Red Hat OpenShift Container Platform 4 openshift/ose-rhel-coreos-8, openshift/ose-rhel-coreos-9
    affected: workaround, 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 1.25.1-2.hum1, unbound-libs 1.25.1-2.hum1, unbound-munin 1.25.1-2.hum1, unbound-utils 1.25.1-2.hum1, unbound-anchor 1.25.1-2.hum1, unbound-dracut 1.25.1-2.hum1, +1 more
    fixed: vendor fix RHSA-2026:24013

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
5mo ago

Exploit prediction

0.65% chance of exploitation in the next 30 days, higher than 51% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by version score vector
CNA 4.0 6.9 CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/U:Amber
CISA ADP 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CNA 4.0 6.9 CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:X/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 5.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
CNA 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected products

  • NLnet Labs Unbound
  • Red Hat Red Hat Enterprise Linux 10
  • Red Hat Red Hat Enterprise Linux 8
  • Red Hat Red Hat Enterprise Linux 9
  • Red Hat Red Hat Hardened Images
  • Red Hat Red Hat Enterprise Linux 6
  • Red Hat Red Hat Enterprise Linux 7
  • Red Hat Red Hat OpenShift Container Platform 4

Classification

Weakness
  • CWE-407 Inefficient Algorithmic Complexity
  • CWE-1050 Excessive Platform Resource Consumption within a Loop

References

Sources

Fencer Intel 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.