SEPTEMBER 20, 2026
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Case File

CVE-2026-44621

MEDIUM · CVSS 5.9 EPSS 0.25%

Source: NVD + CISA KEV + EPSS · Published 2026-07-22 · Last synced 2026-08-21

CyberRota Analysis

AI-Generated

Applications utilizing libunbound versions up to 1.25.1, configured with a non-zero 'unwanted-reply-threshold', are vulnerable to abrupt termination when the threshold is exceeded due to the absence of the 'libworker_alloc_cleanup' function in the allowed function call list. This can lead to a fatal exit of libunbound, impacting the stability of the embedding application. Organizations using libunbound in their applications should prioritize addressing this vulnerability to prevent potential service disruptions.

CVE
CVE-2026-44621
Severity
MEDIUM
CVSS
5.9
EPSS
0.25%

Original NVD 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.

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