Description
In NLnet Labs Unbound 1.22.0 up to and including 1.25.1, in DNS-over-QUIC environments, with high concurrency and under pressure, an assertion in libngtcp2 about monotonic timestamps could trigger and result in server termination and thus denial of service. When interfacing with libngtcp2, for DNS-over-QUIC support in Unbound, it is expected to use monotonic time. Unbound was using realtime instead, and in DoQ environments with high concurrency and under pressure, an assert in libngtcp2 for the quic timestamp would trigger and terminate the server.This vulnerability needs Unbound to be compiled with DoQ support ('--with-libngtcp2') and the 'quic-port' to be configured for the listening interfaces.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| NLnet Labs | Unbound | 1.22.0 – < 1.25.2 | 1.25.2 |
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 | 1.25.2-1 | — |
| Debian 13 | unbound | 1.26.1-0+deb13u1 | — |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 26.10 | unbound | No fix yet | — |
| Ubuntu 26.04 LTS | unbound | No fix yet | — |
| Ubuntu 24.04 LTS | unbound | No fix yet | — |
| Ubuntu 22.04 LTS | unbound | No fix yet | — |
Show 4 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu Pro 20.04 LTS | unbound | No fix yet | — |
| 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 |
|---|---|---|---|
| Red Hat Hardened Images 1 | unbound +7 | 1.25.2-0.1.hum1 | RHSA-2026:43588 |
SUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES for SAP 16.0 | unbound | 1.25.2-160000.1.1 | SUSE-SU-2026:23226-1, SUSE-SU-2026:23215-1 |
| SLES 16.0 | unbound | 1.25.2-160000.1.1 | SUSE-SU-2026:23226-1, SUSE-SU-2026:23215-1 |
| SLE Micro 6.2 | unbound | 1.25.2-160000.1.1 | SUSE-SU-2026:23050-1 |
Show 2 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLE Micro 6.1 | unbound | 1.25.2-slfo.1.1_1.1 | SUSE-SU-2026:23349-1 |
| SLE Micro 6.0 | unbound | 1.25.2-1.1 | SUSE-SU-2026:23360-1 |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Tumbleweed | unbound | 1.25.2-1.1 | openSUSE-SU-2026:11380-1 |
| openSUSE Leap 16.0 | unbound | 1.25.2-160000.1.1 | openSUSE-SU-2026:21550-1 |
Azure Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Azure Linux 3 | unbound | 1.25.2-1 | — |
Advisories 10
- WID-SEC-2026-2492 Unbound: Mehrere Schwachstellen BSI CERT-Bund (WID) · Nov 10, 2026
- RHSA-2026:43588 Red Hat Security Advisory: Red Hat Hardened Images RPMs bug fix and enhancement update Red Hat Security Advisories (RHSA) · Oct 20, 2026
- SUSE-SU-2026:23360-1 Security update for unbound SUSE / openSUSE Security Updates · Sep 10, 2026
- SUSE-SU-2026:23349-1 Security update for unbound SUSE / openSUSE Security Updates · Sep 10, 2026
- SUSE-SU-2026:23226-1 Security update for unbound SUSE / openSUSE Security Updates · Aug 27, 2026
- SUSE-SU-2026:23215-1 Security update for unbound SUSE / openSUSE Security Updates · Aug 27, 2026
- WID-SEC-2026-3038 Meinberg LANTIME: Mehrere Schwachstellen BSI CERT-Bund (WID) · Aug 26, 2026
- openSUSE-SU-2026:21550-1 Security update for unbound SUSE / openSUSE Security Updates · Aug 12, 2026
- SUSE-SU-2026:23050-1 Security update for unbound SUSE / openSUSE Security Updates · Aug 12, 2026
- openSUSE-SU-2026:11380-1 libunbound8-1.25.2-1.1 on GA media SUSE / openSUSE Security Updates · Jul 27, 2026
References
- https://www.nlnetlabs.nl/downloads/unbound/CVE-2026-14586.txt vendor-advisory