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Vulnerabilities / CVE-2026-33278

critical

CVE-2026-33278

unbound: Unbound DNSSEC Validator Use-After-Free via Deep Copy Pointer Overwrite Leading to DoS and Possible Remote Code Execution

Published Modified CWE 416, 672
In the Trivy database since at least 24 Oct 2026, 07:11 UTCWhen it arrived before that build is not recorded.

Severity by source

NVD9.8CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Red Hat8.1CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

Trivy's own label is CRITICAL. Rated critical by NVD, Azure Linux, Photon OS. Rated lower by Red Hat (high), AlmaLinux (high), Amazon (high), Oracle (high), Rocky Linux (high), Ubuntu (high).

Description

NLnet Labs Unbound 1.19.1 up to and including version 1.25.0 has a vulnerability in the DNSSEC validator that enables denial of service and possible remote code execution as a result of deep copying a data structure and erroneously overwriting a destination pointer. An adversary can exploit the vulnerability by controlling a malicious signed zone and querying a vulnerable Unbound. When DS sub-queries need to suspend validation due to NSEC3 computational budget exhaustion (introduced in Unbound 1.19.1), Unbound deep-copies response messages to preserve them across memory region teardown. A struct-assignment bug overwrites the destination's pointer with the source's pointer. After the sub-query region is freed, the resumed validator dereferences this dangling pointer, triggering a crash or potentially enabling arbitrary code execution. Unbound 1.25.1 contains a patch with a fix to preserve the correct pointer when deep copying the data structure.

Affected packages and fixed versions

SourcePackageFixed in
Azure Linux 3.0unbound0:1.25.1-1.azl3
Photon OS 4.0unbound, unbound-devel, unbound-docs1.25.1-1.ph4
Photon OS 5.0unbound, unbound-devel, unbound-docs1.25.1-1.ph5
alma 10python3-unbound, unbound, unbound-anchor and 4 more1.24.2-7.el10_2.1
alma 9python3-unbound, unbound, unbound-devel and 2 more1.24.2-3.el9_8.1
alpine 3.22unbound1.25.2-r0
alpine 3.23unbound1.25.2-r0
alpine 3.24unbound1.25.1-r0
alpine edgeunbound1.25.1-r0
amazon linux 2python2-unbound, python3-unbound, unbound and 3 more1.7.3-15.amzn2.0.14
amazon linux 2023python3-unbound, python3-unbound-debuginfo, unbound and 9 more1.17.1-1.amzn2023.0.12
debian 11unboundno fix listed
Show all 137 entries from 41 sources
SourcePackageFixed in
Azure Linux 3.0unbound0:1.25.1-1.azl3
Photon OS 4.0unbound1.25.1-1.ph4
Photon OS 4.0unbound-devel1.25.1-1.ph4
Photon OS 4.0unbound-docs1.25.1-1.ph4
Photon OS 5.0unbound1.25.1-1.ph5
Photon OS 5.0unbound-devel1.25.1-1.ph5
Photon OS 5.0unbound-docs1.25.1-1.ph5
alma 10python3-unbound1.24.2-7.el10_2.1
alma 10unbound1.24.2-7.el10_2.1
alma 10unbound-anchor1.24.2-7.el10_2.1
alma 10unbound-devel1.24.2-7.el10_2.1
alma 10unbound-dracut1.24.2-7.el10_2.1
alma 10unbound-libs1.24.2-7.el10_2.1
alma 10unbound-utils1.24.2-7.el10_2.1
alma 9python3-unbound1.24.2-3.el9_8.1
alma 9unbound1.24.2-3.el9_8.1
alma 9unbound-devel1.24.2-3.el9_8.1
alma 9unbound-dracut1.24.2-3.el9_8.1
alma 9unbound-libs1.24.2-3.el9_8.1
alpine 3.22unbound1.25.2-r0
alpine 3.23unbound1.25.2-r0
alpine 3.24unbound1.25.1-r0
alpine edgeunbound1.25.1-r0
amazon linux 2python2-unbound1.7.3-15.amzn2.0.14
amazon linux 2python3-unbound1.7.3-15.amzn2.0.14
amazon linux 2unbound1.7.3-15.amzn2.0.14
amazon linux 2unbound-debuginfo1.7.3-15.amzn2.0.14
amazon linux 2unbound-devel1.7.3-15.amzn2.0.14
amazon linux 2unbound-libs1.7.3-15.amzn2.0.14
amazon linux 2023python3-unbound1.17.1-1.amzn2023.0.12
amazon linux 2023python3-unbound-debuginfo1.17.1-1.amzn2023.0.12
amazon linux 2023unbound1.17.1-1.amzn2023.0.12
amazon linux 2023unbound-anchor1.17.1-1.amzn2023.0.12
amazon linux 2023unbound-anchor-debuginfo1.17.1-1.amzn2023.0.12
amazon linux 2023unbound-debuginfo1.17.1-1.amzn2023.0.12
amazon linux 2023unbound-debugsource1.17.1-1.amzn2023.0.12
amazon linux 2023unbound-devel1.17.1-1.amzn2023.0.12
amazon linux 2023unbound-libs1.17.1-1.amzn2023.0.12
amazon linux 2023unbound-libs-debuginfo1.17.1-1.amzn2023.0.12
amazon linux 2023unbound-utils1.17.1-1.amzn2023.0.12
amazon linux 2023unbound-utils-debuginfo1.17.1-1.amzn2023.0.12
debian 11unboundno fix listed
debian 12unboundno fix listed
debian 13unbound1.22.0-2+deb13u3
debian 14unbound1.25.1-1
echounbound1.22.0-2+deb13u3
Oracle Linux 9python3-unbound1.24.2-3.el9_8.1
Oracle Linux 9unbound1.24.2-3.el9_8.1
Oracle Linux 9unbound-devel1.24.2-3.el9_8.1
Oracle Linux 9unbound-dracut1.24.2-3.el9_8.1
Oracle Linux 9unbound-libs1.24.2-3.el9_8.1
rapidfort alma 10python3-unbound1.24.2-7.el10_2.1
rapidfort alma 10unbound0:1.24.2-7.el10_2.1
rapidfort alma 10unbound-anchor0:1.24.2-7.el10_2.1
rapidfort alma 10unbound-devel1.24.2-7.el10_2.1
rapidfort alma 10unbound-dracut1.24.2-7.el10_2.1
rapidfort alma 10unbound-libs0:1.24.2-7.el10_2.1
rapidfort alma 10unbound-utils1.24.2-7.el10_2.1
rapidfort alma 9python3-unbound1.24.2-3.el9_8.1
rapidfort alma 9unbound0:1.24.2-3.el9_8.1
rapidfort alma 9unbound-dracut1.24.2-3.el9_8.1
rapidfort alma 9unbound-libs0:1.24.2-3.el9_8.1
rapidfort alpine 3.20unbound1.25.1-r0
rapidfort alpine 3.21unbound1.25.1-r0
rapidfort alpine 3.22unbound1.25.1-r0
rapidfort alpine 3.23unbound1.25.1-r0
rapidfort amazon linux 2023python3-unbound1.17.1-1.amzn2023.0.12
rapidfort amazon linux 2023unbound0:1.17.1-1.amzn2023.0.12
rapidfort amazon linux 2023unbound-anchor0:1.17.1-1.amzn2023.0.12
rapidfort amazon linux 2023unbound-devel1.17.1-1.amzn2023.0.12
rapidfort amazon linux 2023unbound-libs0:1.17.1-1.amzn2023.0.12
rapidfort amazon linux 2023unbound-utils1.17.1-1.amzn2023.0.12
rapidfort debian 12rf-unbound0:1.26.0-1
rapidfort debian 12unbound0:1.22.0-2+deb13u3, 0:1.25.1-1
rapidfort debian 13rf-unbound0:1.26.0-1
rapidfort debian 13unbound0:1.22.0-2+deb13u3, 0:1.25.1-1
rapidfort fedora 41rf-unbound0:1.24.1-2.fc41
rapidfort fedora 41rf-unbound-anchor0:1.24.1-2.fc41
rapidfort fedora 41rf-unbound-libs0:1.24.1-2.fc41
rapidfort fedora 41unbound0:1.24.1-2.fc41
rapidfort fedora 41unbound-anchor0:1.24.1-2.fc41
rapidfort fedora 41unbound-libs0:1.24.1-2.fc41
rapidfort fedora 43python3-unbound1.25.1-1.fc43
rapidfort fedora 43rf-unbound0:1.25.1-1.fc43
rapidfort fedora 43rf-unbound-anchor0:1.25.1-1.fc43
rapidfort fedora 43rf-unbound-libs0:1.25.1-1.fc43
rapidfort fedora 43unbound0:1.25.1-1.fc43
rapidfort fedora 43unbound-anchor0:1.25.1-1.fc43
rapidfort fedora 43unbound-devel1.25.1-1.fc43
rapidfort fedora 43unbound-dracut1.25.1-1.fc43
rapidfort fedora 43unbound-libs0:1.25.1-1.fc43
rapidfort fedora 43unbound-munin1.25.1-1.fc43
rapidfort fedora 43unbound-utils1.25.1-1.fc43
rapidfort Oracle Linux 10python3-unbound0:1.24.2-7.el10_2.2
rapidfort Oracle Linux 10unbound0:1.24.2-7.el10_2.2
rapidfort Oracle Linux 10unbound-anchor0:1.24.2-7.el10_2.2
rapidfort Oracle Linux 10unbound-devel0:1.24.2-7.el10_2.2
rapidfort Oracle Linux 10unbound-dracut0:1.24.2-7.el10_2.2
rapidfort Oracle Linux 10unbound-libs0:1.24.2-7.el10_2.2
rapidfort Oracle Linux 10unbound-utils0:1.24.2-7.el10_2.2
rapidfort Oracle Linux 9python3-unbound0:1.24.2-3.el9_8.1
rapidfort Oracle Linux 9unbound0:1.24.2-3.el9_8.1
rapidfort Oracle Linux 9unbound-devel0:1.24.2-3.el9_8.1
rapidfort Oracle Linux 9unbound-dracut0:1.24.2-3.el9_8.1
rapidfort Oracle Linux 9unbound-libs0:1.24.2-3.el9_8.1
rapidfort rocky 9python3-unbound0:1.24.2-3.el9_8.1
rapidfort rocky 9rf-unbound0:1.24.2-3.el9_8.1
rapidfort rocky 9rf-unbound-libs0:1.24.2-3.el9_8.1
rapidfort rocky 9unbound0:1.24.2-3.el9_8.1
rapidfort rocky 9unbound-dracut0:1.24.2-3.el9_8.1
rapidfort rocky 9unbound-libs0:1.24.2-3.el9_8.1
rapidfort ubuntu 20.04rf-unbound0:1.13.1-1ubuntu5.14, 0:1.19.2-1ubuntu3.8, 0:1.24.2-1ubuntu2.1
rapidfort ubuntu 20.04unbound0:1.13.1-1ubuntu5.14, 0:1.19.2-1ubuntu3.8, 0:1.24.2-1ubuntu2.1
rapidfort ubuntu 22.04rf-unbound0:1.13.1-1ubuntu5.14, 0:1.19.2-1ubuntu3.8, 0:1.24.2-1ubuntu2.1
rapidfort ubuntu 22.04unbound0:1.13.1-1ubuntu5.14, 0:1.19.2-1ubuntu3.8, 0:1.24.2-1ubuntu2.1
rapidfort ubuntu 24.04rf-unbound0:1.13.1-1ubuntu5.14, 0:1.19.2-1ubuntu3.8, 0:1.24.2-1ubuntu2.1
rapidfort ubuntu 24.04unbound0:1.13.1-1ubuntu5.14, 0:1.19.2-1ubuntu3.8, 0:1.24.2-1ubuntu2.1
Red Hatopenshift/ose-rhel-coreos-9no fix listed
Red Hatunboundno fix listed
Red Hatunbound-develno fix listed
Red Hatunbound-libsno fix listed
Red Hatunbound-pythonno fix listed
rocky 10python3-unbound1.24.2-7.el10_2.1
rocky 10unbound1.24.2-7.el10_2.1
rocky 10unbound-anchor1.24.2-7.el10_2.1
rocky 10unbound-dracut1.24.2-7.el10_2.1
rocky 10unbound-libs1.24.2-7.el10_2.1
rocky 10unbound-utils1.24.2-7.el10_2.1
rocky 9python3-unbound1.24.2-3.el9_8.1
rocky 9unbound1.24.2-3.el9_8.1
rocky 9unbound-dracut1.24.2-3.el9_8.1
rocky 9unbound-libs1.24.2-3.el9_8.1
seal Red Hat 8seal-unbound1.16.2-5.8.el8_10+sp2
seal Red Hat 8unbound1.16.2-5.8.el8_10+sp2
ubuntu 24.04unbound1.19.2-1ubuntu3.8
ubuntu 25.10unbound1.22.0-2ubuntu2.3
ubuntu 26.04unbound1.24.2-1ubuntu2.1

References

All 24 references

Vulnerability data compiled from the Trivy vulnerability database (trivy-db, Aqua Security, Apache License 2.0), which aggregates third-party advisories. CVE records are published by The MITRE Corporation under the CVE Terms of Use; CVE is a trademark of MITRE. This product uses data from the NVD API but is not endorsed or certified by the NVD. Severity, titles and advisory data from the GitHub Advisory Database (CC BY 4.0), Red Hat security data (CC BY 4.0) and the other sources linked on each entry. Entries may be summarised or re-formatted; the linked original is the authoritative record.