Описание
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.
A flaw was found in Unbound. Under heavy DNS-over-QUIC (DoQ) traffic, a timing discrepancy in Unbound’s libngtcp2 library can trigger an assertion failure. This causes the server to crash unexpectedly, resulting in a denial of service (DoS).
Отчет
Moderate: This Unbound vulnerability, leading to a denial of service, is contingent on the resolver being compiled with DNS-over-QUIC (DoQ) support and having a quic-port configured. The flaw manifests under high concurrency and network pressure due to a timing discrepancy in the libngtcp2 library. Red Hat deployments not utilizing DoQ or without the quic-port enabled are not affected.
Меры по смягчению последствий
Disable DNS-over-QUIC (DoQ) by removing or commenting out any quic-port directives in your unbound.conf file. Restart the unbound service for the changes to take effect and prevent potential assertion crashes.
Затронутые пакеты
| Платформа | Пакет | Состояние | Рекомендация | Релиз |
|---|---|---|---|---|
| Red Hat Enterprise Linux 10 | unbound | Fix deferred | ||
| Red Hat Enterprise Linux 6 | unbound | Not affected | ||
| Red Hat Enterprise Linux 7 | unbound | Not affected | ||
| Red Hat Enterprise Linux 8 | unbound | Not affected | ||
| Red Hat Enterprise Linux 9 | unbound | Fix deferred | ||
| Red Hat OpenShift Container Platform 4 | rhcos | Fix deferred | ||
| Red Hat Hardened Images | unbound-main-1.25.2-0.1.hum1 | Fixed | RHSA-2026:43588 | 22.07.2026 |
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Дополнительная информация
Статус:
EPSS
5.9 Medium
CVSS3
Связанные уязвимости
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.
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.
Assertion in libngtcp2 when under pressure in high concurrency DNS-over-QUIC environments
In NLnet Labs Unbound 1.22.0 up to and including 1.25.1, in DNS-over-Q ...
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.
EPSS
5.9 Medium
CVSS3