CVE-2026-44621

Public on 2026-07-22
Modified on 2026-07-27
Description
With NLnet Labs Unbound up to and including version 1.25.1, applications using libunbound and configured with 'unwanted-reply-threshold', could eventually be abruptly terminated if the threshold is reached and libunbound needs to call 'libworker_alloc_cleanup' since the function is absent from the function call allow list. When an application using libunbound sets 'unwanted-reply-threshold' to any non-zero value and the iterator queries an authoritative that replies with enough wrong-transaction-ID UDP datagrams to cross the threshold, the 'libworker_alloc_cleanup' will eventually be called. Since the function is absent from the function call allow list, this leads to a fatal exit of libunbound and eventual termination of the embedding application.Unbound itself is not affected since its relevant function 'worker_alloc_cleanup' is registed in the allow list and proceeds to perform the documented cache flush.
Severity
Medium severity
Medium
See what this means
CVSS v3 Base Score
5.9
See breakdown

Affected Packages

Platform Package Release Date Advisory Status
Amazon Linux 2 - Core unbound Pending Fix
Amazon Linux 2 - Unbound1.17 Extra unbound Pending Fix
Amazon Linux 2023 unbound Pending Fix

CVSS Scores

Score Type Score Vector
Amazon Linux CVSSv3 5.9 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H