GHSA-3M86-WJGW-CGQC
Vulnerability from github – Published: 2026-07-22 15:31 – Updated: 2026-07-22 15:31With 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.
{
"affected": [],
"aliases": [
"CVE-2026-44621"
],
"database_specific": {
"cwe_ids": [
"CWE-754"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-07-22T14:17:18Z",
"severity": "MODERATE"
},
"details": "With NLnet Labs Unbound up to and including version 1.25.1, applications using libunbound and configured with \u0027unwanted-reply-threshold\u0027, could eventually be abruptly terminated if the threshold is reached and libunbound needs to call \u0027libworker_alloc_cleanup\u0027 since the function is absent from the function call allow list. When an application using libunbound sets \u0027unwanted-reply-threshold\u0027 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 \u0027libworker_alloc_cleanup\u0027 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 \u0027worker_alloc_cleanup\u0027 is registed in the allow list and proceeds to perform the documented cache flush.",
"id": "GHSA-3m86-wjgw-cgqc",
"modified": "2026-07-22T15:31:24Z",
"published": "2026-07-22T15:31:24Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-44621"
},
{
"type": "WEB",
"url": "https://www.nlnetlabs.nl/downloads/unbound/CVE-2026-44621.txt"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H",
"type": "CVSS_V3"
}
]
}
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