Description
The DNS protocol in RFC 1035 and updates allows remote attackers to cause a denial of service (resource consumption) by arranging for DNS queries to be accumulated for seconds, such that responses are later sent in a pulsing burst (which can be considered traffic amplification in some cases), aka the "DNSBomb" issue.
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 14 | unbound | 1.20.0-1 | — |
| Debian 13 | unbound | 1.20.0-1 | — |
| Debian 12 | unbound | 1.17.1-2+deb12u3 | DSA-5987-1 |
| Debian 11 | unbound | 1.13.1-1+deb11u5 | DLA-4280-1 |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 24.04 LTS | unbound | 1.19.2-1ubuntu3.1 | USN-6791-1 |
| Ubuntu 22.04 LTS | unbound | 1.13.1-1ubuntu5.5 | USN-6791-1 |
| Ubuntu 20.04 LTS | unbound | 1.9.4-2ubuntu1.6 | USN-6791-1 |
Show 3 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu Pro 18.04 LTS | unbound | No fix yet | — |
| Ubuntu Pro 16.04 LTS | unbound | No fix yet | — |
| Ubuntu Pro 14.04 LTS | unbound | No fix yet | — |
Red Hat
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| RHEL 10 | unbound +6 | 1.24.2-7.el10 | RHSA-2026:18556 |
| RHEL 9 | unbound +4 | 1.24.2-2.el9 | RHSA-2026:18931 |
AlmaLinux
Errata ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| AlmaLinux 10 | unbound +6 | 1.24.2-7.el10 | ALSA-2026:18556 |
| AlmaLinux 9 | unbound +4 | 1.24.2-2.el9 | ALSA-2026:18931 |
Rocky Linux
Errata ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Rocky Linux 10 | unbound | 1.24.2-7.el10 | RLSA-2026:18556 |
| Rocky Linux 9 | unbound | 1.24.2-2.el9 | RLSA-2026:18931 |
SUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLE Micro 6.0 | unbound | 1.21.0-1.1 | SUSE-SU-2025:20024-1 |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Tumbleweed | unbound | 1.20.0-1.1 | openSUSE-SU-2024:13944-1 |
Alpine
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine v3.24 | unbound | 1.20.0-r0 | — |
| Alpine v3.23 | unbound | 1.20.0-r0 | — |
| Alpine v3.22 | unbound | 1.20.0-r0 | — |
| Alpine v3.21 | unbound | 1.20.0-r0 | — |
| Alpine v3.20 | unbound | 1.20.0-r0 | — |
Show 3 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine v3.19 | unbound | 1.20.0-r0 | — |
| Alpine v3.18 | unbound | 1.20.0-r0 | — |
| Alpine v3.17 | unbound | 1.20.0-r0 | — |
Amazon Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Amazon Linux 2023 | unbound +5 | 1.17.1-1.amzn2023.0.4 | ALAS2023-2024-610 |
| Amazon Linux 2 | unbound +4 | 1.7.3-15.amzn2.0.8 | ALAS2-2024-2536 |
Azure Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Azure Linux 3 | unbound | 1.19.1-3 | — |
| Azure Linux 2 (CBL-Mariner) | unbound | 1.19.1-3 | — |
Oracle Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Oracle Linux 10 | unbound +6 | 1.24.2-7.el10 | ELSA-2026-18556 |
| Oracle Linux 9 | unbound +4 | 1.24.2-2.el9 | ELSA-2026-18931 |
Advisories 15
- ALSA-2026:18931 Moderate: unbound security update AlmaLinux Security Advisories · Oct 29, 2026
- ALSA-2026:18556 Moderate: unbound security update AlmaLinux Security Advisories · Oct 29, 2026
- RHSA-2026:18931 Red Hat Security Advisory: unbound security update Red Hat Security Advisories (RHSA) · Sep 2, 2026
- RHSA-2026:18556 Red Hat Security Advisory: unbound security update Red Hat Security Advisories (RHSA) · Sep 2, 2026
- ELSA-2026-18556 Moderate: unbound security update (Oracle Linux 10) Oracle Linux Security Advisories (ELSA) · Jul 8, 2026
- ELSA-2026-18931 Moderate: unbound security update (Oracle Linux 9) Oracle Linux Security Advisories (ELSA) · Jun 12, 2026
- RLSA-2026:18556 Moderate: unbound security update Rocky Linux Security Advisories · May 29, 2026
- RLSA-2026:18931 Moderate: unbound security update Rocky Linux Security Advisories · May 28, 2026
- USN-6791-1 unbound vulnerability Ubuntu Security Notices (USN) · Apr 27, 2026
- SUSE-SU-2025:20024-1 Security update for unbound SUSE / openSUSE Security Updates · Mar 23, 2026
- DSA-5987-1 unbound - security update Debian Security (DSA / DLA) · Mar 9, 2026
- DLA-4280-1 unbound - security update Debian Security (DSA / DLA) · Mar 9, 2026
- openSUSE-SU-2024:13944-1 libunbound8-1.20.0-1.1 on GA media SUSE / openSUSE Security Updates · Feb 4, 2026
- ALAS2023-2024-610 Important: unbound security update (Amazon Linux 2023) Amazon Linux Security Center (ALAS) · May 15, 2024
- ALAS2-2024-2536 Important: unbound security update (Amazon Linux 2) Amazon Linux Security Center (ALAS) · May 15, 2024
References
- https://datatracker.ietf.org/doc/html/rfc1035
- https://nlnetlabs.nl/projects/unbound/security-advisories/
- https://github.com/TechnitiumSoftware/DnsServer/blob/master/CHANGELOG.md#version-120
- https://www.isc.org/blogs/2024-dnsbomb/
- https://nlnetlabs.nl/downloads/unbound/CVE-2024-33655.txt
- https://github.com/NLnetLabs/unbound/commit/c3206f4568f60c486be6d165b1f2b5b254fea3de
- https://alas.aws.amazon.com/ALAS-2024-1934.html
- https://meterpreter.org/researchers-uncover-dnsbomb-a-new-pdos-attack-exploiting-legitimate-dns-features/
- https://sp2024.ieee-security.org/accepted-papers.html
- https://gitlab.isc.org/isc-projects/bind9/-/issues/4398
- FEDORA-2024-9df760819c vendor-advisory
- FEDORA-2024-68626e0eb5 vendor-advisory