1. Ubuntu Security Notices
  2. USN-8282-1

USN-8282-1: Unbound vulnerabilities

Publication date

20 May 2026

Overview

Several security issues were fixed in Unbound.

Releases

Packages

  • unbound - validating, recursive, caching DNS resolver

Details

Andrew Griffiths discovered that Unbound did not properly handle certain
DNSCrypt packets. A remote attacker could possibly use this issue to cause
Unbound to crash, resulting in a denial of service. (CVE-2026-32792)

Qifan Zhang discovered that Unbound incorrectly handled DNSSEC validation
in certain situations. A remote attacker could possibly use this issue to
execute arbitrary code. This issue only affected Ubuntu 24.04 LTS,
Ubuntu 25.10, and Ubuntu 26.04 LTS. (CVE-2026-33278)

Qifan Zhang discovered that Unbound incorrectly handled certain ghost
domain name records. A remote attacker could possibly use this issue to
cause a denial of service. This issue only affected Ubuntu 24.04 LTS,
Ubuntu 25.10, and Ubuntu 26.04 LTS. (CVE-2026-40622)

Qifan Zhang discovered that Unbound did not properly limit processing...

Andrew Griffiths discovered that Unbound did not properly handle certain
DNSCrypt packets. A remote attacker could possibly use this issue to cause
Unbound to crash, resulting in a denial of service. (CVE-2026-32792)

Qifan Zhang discovered that Unbound incorrectly handled DNSSEC validation
in certain situations. A remote attacker could possibly use this issue to
execute arbitrary code. This issue only affected Ubuntu 24.04 LTS,
Ubuntu 25.10, and Ubuntu 26.04 LTS. (CVE-2026-33278)

Qifan Zhang discovered that Unbound incorrectly handled certain ghost
domain name records. A remote attacker could possibly use this issue to
cause a denial of service. This issue only affected Ubuntu 24.04 LTS,
Ubuntu 25.10, and Ubuntu 26.04 LTS. (CVE-2026-40622)

Qifan Zhang discovered that Unbound did not properly limit processing of
long EDNS option lists. A remote attacker could possibly use this issue to
cause Unbound to use excessive resources, leading to a denial of service.
(CVE-2026-41292)

Qifan Zhang discovered that Unbound incorrectly handled jostle logic under
certain circumstances. A remote attacker could possibly use this issue to
cause Unbound to use excessive resources, leading to a denial of service.
(CVE-2026-42534)

Qifan Zhang discovered that Unbound did not properly bound NSEC3 hash
calculations. A remote attacker could possibly use this issue to cause
Unbound to use excessive resources, leading to a denial of service.
(CVE-2026-42923)

Qifan Zhang discovered that Unbound incorrectly handled multiple EDNS
options in certain situations. A remote attacker could possibly use this
issue to cause Unbound to crash, resulting in a denial of service, or
execute arbitrary code. This issue only affected Ubuntu 24.04 LTS,
Ubuntu 25.10, and Ubuntu 26.04 LTS. (CVE-2026-42944)

Qifan Zhang discovered that Unbound incorrectly handled DNSSEC validation
of malicious content. A remote attacker could possibly use this issue to
cause Unbound to crash, resulting in a denial of service.
(CVE-2026-42959)

TaoFei Guo, Yang Luo, and JianJun Chen discovered that Unbound
incorrectly handled delegation processing in certain situations. A remote
attacker could possibly use this issue to poison the DNS cache and obtain
sensitive information. (CVE-2026-42960)

Qifan Zhang discovered that Unbound did not properly bound name
compression in certain cases. A remote attacker could possibly use this
issue to cause Unbound to use excessive resources, leading to a denial of
service. (CVE-2026-44390)

Qifan Zhang discovered that Unbound had a use-after-free issue in RPZ
handling. A remote attacker could possibly use this issue to cause Unbound
to crash, resulting in a denial of service, or execute arbitrary code.
This issue only affected Ubuntu 24.04 LTS, Ubuntu 25.10, and Ubuntu 26.04
LTS. (CVE-2026-44608)

Update instructions

In general, a standard system update will make all the necessary changes.

Learn more about how to get the fixes.

The problem can be corrected by updating your system to the following package versions:

Ubuntu Release Package Version
26.04 LTS resolute libunbound8 –  1.24.2-1ubuntu2.1
unbound –  1.24.2-1ubuntu2.1
25.10 questing libunbound8 –  1.22.0-2ubuntu2.3
unbound –  1.22.0-2ubuntu2.3
24.04 LTS noble libunbound8 –  1.19.2-1ubuntu3.8
unbound –  1.19.2-1ubuntu3.8
22.04 LTS jammy libunbound8 –  1.13.1-1ubuntu5.15
unbound –  1.13.1-1ubuntu5.15

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References

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