Input validation error in Unbound - CVE-2026-44690

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Main Vulnerability Database Vulnerabilities #VU139234

Input validation error in Unbound - CVE-2026-44690

Published: July 23, 2026


Vulnerability identifier: #VU139234
CSH Severity: High
CVSS v4: 8.7 [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]
CVE-ID: CVE-2026-44690
CWE-ID: CWE-20
Exploitation vector: Remote access
Exploit availability: No public exploit available

Vulnerability details

The vulnerability allows a remote attacker to poison the DNS cache and cause DNS responses for arbitrary sibling zones to be treated as insecure.

The vulnerability exists due to improper input validation in aggressive NSEC processing when processing malicious DNS responses containing fraudulent wildcard DS records and invalid RRSIG labels. A remote attacker can control a single delegated zone and serve crafted DNS responses to poison the DNS cache and cause DNS responses for arbitrary sibling zones to be treated as insecure.

Exploitation requires Unbound to be configured with aggressive-nsec and the attacker to control one registered domain under an NSEC-signed parent domain.


Affected software

Unbound
SUSE Linux Enterprise Server 15 SP6
SUSE Linux Enterprise Server 15 SP5
SUSE Linux Enterprise Server 15 SP4
SUSE Linux Enterprise High Performance Computing LTSS 15
SUSE Linux Enterprise High Performance Computing ESPOS 15
SUSE Linux Enterprise Server for SAP Applications 15
SUSE Linux Enterprise Server 15
SUSE Linux Enterprise High Performance Computing 15
SUSE Linux Enterprise Desktop 15
SUSE Linux Enterprise Real Time 15
SUSE Linux Enterprise Micro
Anolis OS
Red Hat Enterprise Linux for IBM z Systems
Red Hat Enterprise Linux for Power, little endian
Red Hat Enterprise Linux for ARM 64
Red Hat Enterprise Linux for x86_64
Basesystem Module
SUSE Package Hub 15
openSUSE Leap
openEuler
Fedora
unbound-libs
unbound-help
unbound
python3-unbound
unbound-debuginfo
unbound-debugsource
unbound-devel
unbound-anchor
unbound-utils
unbound-debugsource (Red Hat package)
unbound-devel (Red Hat package)
unbound (Red Hat package)
libunbound8-debuginfo
unbound-anchor-debuginfo
libunbound8
libunbound-devel-mini
libunbound-devel-mini-debugsource
libunbound-devel-mini-debuginfo
unbound-python-debuginfo
unbound-python
unbound-munin

How to mitigate CVE-2026-44690

Install security update from vendor's website.

Unbound - update to 1.25.2
unbound-libs - addressed in versions 1.11.0-25, 1.13.2-25, 1.17.1-19, 1.17.1-20
unbound-help - addressed in versions 1.11.0-25, 1.13.2-25, 1.17.1-19, 1.17.1-20
unbound - addressed in versions 1.11.0-25, 1.13.2-25, 1.17.1-19, 1.17.1-20
python3-unbound - addressed in versions 1.11.0-25, 1.13.2-25, 1.17.1-19, 1.17.1-20
unbound-debuginfo - addressed in versions 1.11.0-25, 1.13.2-25, 1.17.1-19, 1.17.1-20
unbound-debugsource - addressed in versions 1.11.0-25, 1.13.2-25, 1.17.1-19, 1.17.1-20
unbound-devel - addressed in versions 1.11.0-25, 1.13.2-25, 1.17.1-19, 1.17.1-20
unbound-anchor - addressed in versions 1.13.2-25, 1.17.1-19, 1.17.1-20
python3-unbound - addressed in versions 1.16.2-9.0.3, 1.17.1-14
unbound - addressed in versions 1.16.2-9.0.3, 1.17.1-14
unbound-devel - addressed in versions 1.16.2-9.0.3, 1.17.1-14
unbound-libs - addressed in versions 1.16.2-9.0.3, 1.17.1-14
unbound-anchor - update to 1.17.1-14
unbound-utils - update to 1.17.1-14
unbound-utils - addressed in versions 1.17.1-19, 1.17.1-20
unbound-debugsource (Red Hat package) - update to 1.24.2-3.el9_8.4
unbound-devel (Red Hat package) - update to 1.24.2-3.el9_8.4
unbound (Red Hat package) - update to 1.24.2-7.el10_2.4
unbound - update to 1.25.2-1.fc43
libunbound8-debuginfo - addressed in versions 1.25.2-150100.10.28.1, 1.25.2-150600.23.19.1
unbound-debuginfo - addressed in versions 1.25.2-150100.10.28.1, 1.25.2-150600.23.19.1
unbound-anchor-debuginfo - addressed in versions 1.25.2-150100.10.28.1, 1.25.2-150600.23.19.1
unbound-debugsource - addressed in versions 1.25.2-150100.10.28.1, 1.25.2-150600.23.19.1
unbound-anchor - addressed in versions 1.25.2-150100.10.28.1, 1.25.2-150600.23.19.1
unbound-devel - addressed in versions 1.25.2-150100.10.28.1, 1.25.2-150600.23.19.1
libunbound8 - addressed in versions 1.25.2-150100.10.28.1, 1.25.2-150600.23.19.1
libunbound-devel-mini - update to 1.25.2-150600.23.19.1
libunbound-devel-mini-debugsource - update to 1.25.2-150600.23.19.1
libunbound-devel-mini-debuginfo - update to 1.25.2-150600.23.19.1
unbound-python-debuginfo - update to 1.25.2-150600.23.19.1
unbound - update to 1.25.2-150600.23.19.1
unbound-python - update to 1.25.2-150600.23.19.1
unbound-munin - update to 1.25.2-150600.23.19.1

External References

Related Security Bulletins