CVE-2026-14586: 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 timestam
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.
Details
Original advisory: https://nvd.nist.gov/vuln/detail/CVE-2026-14586
Exploitation outlook
EPSS (FIRST.org) estimates each CVE’s probability of exploitation in the next 30 days — here is the CSIRTS.com read on those numbers.
- Low exploitation riskCVE-2026-145860.27% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 19% of all scored CVEs.
Referenced CVEs
| CVE | CSIRTS overview | External |
|---|---|---|
| CVE-2026-14586 | coverage & exploitation status | NVD · CVE.org |
Same CVEs, other sources
How other CERTs, PSIRTs and databases cover the vulnerabilities in this advisory.
Recent advisories for In NLnet Labs
A cluster of recent advisories against the same product widens the attack surface — attackers routinely chain freshly published CVEs on one product, so review these together.
- mediumCVE-2026-56444: In NLnet Labs Unbound 1.20.0 up to and including 1.25.1, when Unbound is configured with 'serv…nvd · 2026-07-22
- mediumCVE-2026-56416: In NLnet Labs Unbound up to and including version 1.25.1, when the validator builds the canoni…nvd · 2026-07-22
- mediumCVE-2026-55991: In NLnet Labs Unbound 1.22.0 up to and including 1.25.1, a remote unauthenticated client can t…nvd · 2026-07-22
- mediumCVE-2026-55990: In NLnet Labs Unbound 1.7.0 up to and including 1.25.1, when the 'dnscrypt:' clause lists more…nvd · 2026-07-22
- highCVE-2026-55973: In NLnet Labs Unbound 1.23.0 up to and including 1.25.1, when 'dns-error-reporting: yes' is se…nvd · 2026-07-22
- mediumCVE-2026-55717: In NLnet Labs Unbound 1.10.0 up to and including 1.25.1, when 'serve-expired: yes' is set toge…nvd · 2026-07-22
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