Description
In NLnet Labs Unbound up to and including 1.26.0, a vulnerability was found in that can progressively corrupt heap memory and under certain systems and compilation options could lead to remote code execution. The vulnerability starts when CNAME synthesis during an upstream response needs to enforce(rewrite) a max TTL value in the packet buffer. Coupled with a compression pointer that points to the overwritten value and invalidates the domain name, it leads to an error path that does not properly move the buffer position and allows for the heap buffer overflow. Since this is heavily reliant on heap memory layout, results are memory corruption that eventually leads to a crash and under specific systems and compilation options remote code execution.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| NLnet Labs | Unbound | < 1.26.1 | 1.26.1 |
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 | 1.26.1-1 | — |
| Debian 13 | unbound | 1.26.1-0+deb13u1 | — |
| Debian 12 | unbound | No fix yet | — |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 26.10 | unbound | No fix yet | — |
| Ubuntu 26.04 LTS | unbound | 1.24.2-1ubuntu2.3 | USN-8873-1 |
| Ubuntu 24.04 LTS | unbound | 1.19.2-1ubuntu3.10 | USN-8873-1 |
| Ubuntu 22.04 LTS | unbound | 1.13.1-1ubuntu5.16 | USN-8873-1 |
Show 4 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu Pro 20.04 LTS | unbound | 1.9.4-2ubuntu1.11+esm2 | USN-8873-1 |
| Ubuntu Pro 18.04 LTS | unbound | 1.6.7-1ubuntu2.6+esm5 | USN-8873-1 |
| Ubuntu Pro 16.04 LTS | unbound | 1.5.8-1ubuntu1.1+esm4 | USN-8873-1 |
| Ubuntu Pro 14.04 LTS | unbound | 1.4.22-1ubuntu4.14.04.3+esm4 | USN-8873-1 |
Red Hat
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| RHEL 10 | unbound +6 | 1.24.2-7.el10_2.6 | RHSA-2026:71419 |
| RHEL 9 | unbound +4 | 1.24.2-3.el9_8.8 | RHSA-2026:71487 |
| RHEL 8 | unbound +3 | 1.16.2-5.14.el8_10.4 | RHSA-2026:70754 |
Show 1 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Red Hat Hardened Images 1 | unbound +7 | 1.26.1-1.hum1 | RHSA-2026:68590 |
AlmaLinux
Errata ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| AlmaLinux 10 | unbound +6 | 1.24.2-7.el10_2.6 | ALSA-2026:71419 |
| AlmaLinux 9 | unbound +4 | 1.24.2-3.el9_8.8 | ALSA-2026:71487 |
| AlmaLinux 8 | unbound +3 | 1.16.2-5.14.el8_10.4 | ALSA-2026:70754 |
Rocky Linux
Errata ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Rocky Linux 10 | unbound | 1.24.2-7.el10_2.6 | RLSA-2026:71419 |
| Rocky Linux 9 | unbound | 1.24.2-3.el9_8.8 | RLSA-2026:71487 |
| Rocky Linux 8 | unbound | 1.16.2-5.14.el8_10.4 | RLSA-2026:70754 |
SUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES 15 SP7 | unbound | 1.26.1-150600.23.24.1 | SUSE-SU-2026:4620-1 |
| SLES 15 SP6 | unbound | 1.26.1-150600.23.24.1 | SUSE-SU-2026:4620-1 |
| SLES 15 SP5 | unbound | 1.26.1-150100.10.31.1 | SUSE-SU-2026:4624-1 |
| SLES 15 SP4 | unbound | 1.26.1-150100.10.31.1 | SUSE-SU-2026:4624-1 |
Show 11 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES for SAP 16.0 | unbound | 1.26.1-160000.1.1 | SUSE-SU-2026:24226-1 |
| SLES for SAP 15 SP6 | unbound | 1.26.1-150600.23.24.1 | SUSE-SU-2026:4620-1 |
| SLES for SAP 15 SP5 | unbound | 1.26.1-150100.10.31.1 | SUSE-SU-2026:4624-1 |
| SLES for SAP 15 SP4 | unbound | 1.26.1-150100.10.31.1 | SUSE-SU-2026:4624-1 |
| SLES 16.0 | unbound | 1.26.1-160000.1.1 | SUSE-SU-2026:24226-1 |
| SLE Micro 6.2 | unbound | 1.26.1-160000.1.1 | SUSE-SU-2026:24128-1 |
| SLE Micro 6.1 | unbound | 1.26.1-slfo.1.1_1.1 | SUSE-SU-2026:24376-1 |
| SLE Micro 6.0 | unbound | 1.26.1-159998.1.1 | SUSE-SU-2026:24135-1 |
| SLE Micro 5.5 | unbound | 1.26.1-150100.10.31.1 | SUSE-SU-2026:4624-1 |
| SLE HPC 15 SP5 | unbound | 1.26.1-150100.10.31.1 | SUSE-SU-2026:4624-1 |
| SLE HPC 15 SP4 | unbound | 1.26.1-150100.10.31.1 | SUSE-SU-2026:4624-1 |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Tumbleweed | unbound | 1.26.1-1.1 | openSUSE-SU-2026:11930-1 |
| openSUSE Leap 16.0 | unbound | 1.26.1-160000.1.1 | openSUSE-SU-2026:22082-1 |
Alpine
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine v3.24 | unbound | 1.25.2-r2 | — |
| Alpine v3.23 | unbound | 1.25.2-r0 | — |
| Alpine v3.22 | unbound | 1.25.2-r0 | — |
Amazon Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Amazon Linux 2023 | unbound +5 | 1.17.1-1.amzn2023.0.15 | ALAS2023-2026-3127 |
| Amazon Linux 2 | unbound +4 | 1.7.3-15.amzn2.0.17 | ALAS2-2026-3941 |
Azure Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Azure Linux 3 | unbound | 1.26.1-1 | — |
Oracle Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Oracle Linux 10 | unbound +6 | 1.24.2-7.el10_2.6 | ELSA-2026-71419 |
| Oracle Linux 9 | unbound +4 | 1.24.2-3.el9_8.8 | ELSA-2026-71487 |
| Oracle Linux 8 | unbound +3 | 1.16.2-5.14.el8_10.4 | ELSA-2026-70754 |
Advisories 25
- WID-SEC-2026-3392 Unbound: Mehrere Schwachstellen BSI CERT-Bund (WID) · Nov 10, 2026
- ALSA-2026:71487 Critical: unbound security update AlmaLinux Security Advisories · Oct 29, 2026
- ALSA-2026:71419 Critical: unbound security update AlmaLinux Security Advisories · Oct 29, 2026
- ALSA-2026:70754 Critical: unbound security update AlmaLinux Security Advisories · Oct 29, 2026
- SUSE-SU-2026:24376-1 Security update for unbound SUSE / openSUSE Security Updates · Oct 27, 2026
- SUSE-SU-2026:24226-1 Security update for unbound SUSE / openSUSE Security Updates · Oct 21, 2026
- openSUSE-SU-2026:22082-1 Security update for unbound SUSE / openSUSE Security Updates · Oct 19, 2026
- RHSA-2026:71487 Red Hat Security Advisory: unbound security update Red Hat Security Advisories (RHSA) · Oct 19, 2026
- RHSA-2026:71419 Red Hat Security Advisory: unbound security update Red Hat Security Advisories (RHSA) · Oct 19, 2026
- RHSA-2026:70754 Red Hat Security Advisory: unbound security update Red Hat Security Advisories (RHSA) · Oct 19, 2026
- RHSA-2026:68590 Red Hat Security Advisory: Red Hat Hardened Images RPMs bug fix and enhancement update Red Hat Security Advisories (RHSA) · Oct 17, 2026
- SUSE-SU-2026:24135-1 Security update for unbound SUSE / openSUSE Security Updates · Oct 15, 2026
- SUSE-SU-2026:24128-1 Security update for unbound SUSE / openSUSE Security Updates · Oct 13, 2026
- SUSE-SU-2026:4620-1 Security update for unbound SUSE / openSUSE Security Updates · Oct 13, 2026
- SUSE-SU-2026:4624-1 Security update for unbound SUSE / openSUSE Security Updates · Oct 13, 2026
- USN-8873-1 unbound vulnerabilities Ubuntu Security Notices (USN) · Oct 6, 2026
- openSUSE-SU-2026:11930-1 libunbound8-1.26.1-1.1 on GA media SUSE / openSUSE Security Updates · Sep 30, 2026
- ALAS2023-2026-3127 Important: unbound security update (Amazon Linux 2023) Amazon Linux Security Center (ALAS) · Sep 28, 2026
- ALAS2-2026-3941 Important: unbound security update (Amazon Linux 2) Amazon Linux Security Center (ALAS) · Sep 28, 2026
- RLSA-2026:71487 Critical: unbound security update Rocky Linux Security Advisories · Sep 25, 2026
- RLSA-2026:71419 Critical: unbound security update Rocky Linux Security Advisories · Sep 25, 2026
- RLSA-2026:70754 Critical: unbound security update Rocky Linux Security Advisories · Sep 24, 2026
- ELSA-2026-71487 Critical: unbound security update (Oracle Linux 9) Oracle Linux Security Advisories (ELSA) · Sep 24, 2026
- ELSA-2026-70754 Critical: unbound security update (Oracle Linux 8) Oracle Linux Security Advisories (ELSA) · Sep 24, 2026
- ELSA-2026-71419 Critical: unbound security update (Oracle Linux 10) Oracle Linux Security Advisories (ELSA) · Sep 24, 2026
References
- https://www.nlnetlabs.nl/downloads/unbound/CVE-2026-82717.txt vendor-advisory