Incorrect calculation in Unbound - CVE-2026-14586
Published: July 23, 2026
Vulnerability identifier: #VU139229
CSH Severity: Medium
CVSS v4.0: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/U:Green
CVE-ID: CVE-2026-14586
CWE-ID: CWE-682
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vendor: NLnet Labs
Affected software:
Unbound
Unbound
Detailed vulnerability description
The vulnerability allows a remote attacker to cause a denial of service.
The vulnerability exists due to improper time source selection in the DNS-over-QUIC interface with libngtcp2 when handling high-concurrency DNS-over-QUIC traffic under pressure. A remote attacker can send concurrent DNS-over-QUIC traffic to trigger an assertion and terminate the server to cause a denial of service.
Only instances compiled with DNS-over-QUIC support and configured to listen on a QUIC port are vulnerable.
How to mitigate CVE-2026-14586
Install security update from vendor's website.