{ "document": { "category": "csaf_vex", "csaf_version": "2.0", "distribution": { "text": "TuxCare License Agreement", "tlp": { "label": "WHITE", "url": "https://www.first.org/tlp/" } }, "lang": "en", "notes": [ { "category": "legal_disclaimer", "text": "This content is licensed under the Creative Commons Attribution 4.0 International License (https://creativecommons.org/licenses/by/4.0/). If you distribute this content, or a modified version of it, you must provide attribution to Cloud Linux Inc. and provide a link to the original.", "title": "Terms of Use" } ], "publisher": { "category": "vendor", "contact_details": "https://tuxcare.com/contact/", "name": "TuxCare", "namespace": "https://tuxcare.com/" }, "references": [ { "category": "self", "summary": "Canonical URL", "url": "https://security.tuxcare.com/csaf/v2/els_os/centos6els/vex/2026/cve-2026-44621-els_os-centos6els.json" } ], "tracking": { "current_release_date": "2026-10-28T10:59:26Z", "generator": { "date": "2026-10-28T10:59:26Z", "engine": { "name": "pyCSAF" } }, "id": "CVE-2026-44621-ELS_OS-CENTOS6ELS", "initial_release_date": "2026-07-22T14:17:00Z", "revision_history": [ { "date": "2026-07-22T14:17:00Z", "number": "1", "summary": "Initial version" }, { "date": "2026-10-28T10:59:26Z", "number": "2", "summary": "Official Publication" } ], "status": "final", "version": "2" }, "title": "Security update on 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"CentOS-6" }, { "category": "default_component_of", "full_product_name": { "name": "unbound-0:1.4.20-29.el6_10.1.x86_64 as a component of Community Enterprise Operating System 6", "product_id": "CentOS-6:unbound-0:1.4.20-29.el6_10.1.x86_64" }, "product_reference": "unbound-0:1.4.20-29.el6_10.1.x86_64", "relates_to_product_reference": "CentOS-6" } ] }, "vulnerabilities": [ { "cve": "CVE-2026-44621", "cwe": { "id": "CWE-754", "name": "Improper Check for Unusual or Exceptional Conditions" }, "notes": [ { "category": "description", "text": "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.", "title": "Vulnerability description" } ], "product_status": { "known_affected": [ "CentOS-6:unbound-0:1.4.20-29.el6_10.1.i686", "CentOS-6:unbound-0:1.4.20-29.el6_10.1.tuxcare.els2.i686", "CentOS-6:unbound-0:1.4.20-29.el6_10.1.tuxcare.els2.x86_64", "CentOS-6:unbound-0:1.4.20-29.el6_10.1.x86_64", "CentOS-6:unbound-devel-0:1.4.20-29.el6_10.1.i686", "CentOS-6:unbound-devel-0:1.4.20-29.el6_10.1.tuxcare.els2.i686", "CentOS-6:unbound-devel-0:1.4.20-29.el6_10.1.tuxcare.els2.x86_64", "CentOS-6:unbound-devel-0:1.4.20-29.el6_10.1.x86_64", "CentOS-6:unbound-libs-0:1.4.20-29.el6_10.1.i686", "CentOS-6:unbound-libs-0:1.4.20-29.el6_10.1.tuxcare.els2.i686", "CentOS-6:unbound-libs-0:1.4.20-29.el6_10.1.tuxcare.els2.x86_64", "CentOS-6:unbound-libs-0:1.4.20-29.el6_10.1.x86_64", "CentOS-6:unbound-python-0:1.4.20-29.el6_10.1.i686", "CentOS-6:unbound-python-0:1.4.20-29.el6_10.1.tuxcare.els2.i686", "CentOS-6:unbound-python-0:1.4.20-29.el6_10.1.tuxcare.els2.x86_64", "CentOS-6:unbound-python-0:1.4.20-29.el6_10.1.x86_64" ] }, "references": [ { "category": "self", "summary": "Canonical URL", "url": "https://cve.tuxcare.com/els/cve/CVE-2026-44621" }, { "category": "external", "summary": "https://www.nlnetlabs.nl/downloads/unbound/CVE-2026-44621.txt", "url": "https://www.nlnetlabs.nl/downloads/unbound/CVE-2026-44621.txt" } ], "release_date": "2026-07-22T14:17:00Z", "remediations": [ { "category": "no_fix_planned", "date": "2026-10-25T11:17:45.241754Z", "details": "This flaw is denial‑of‑service only and is triggered solely in applications that embed libunbound and explicitly set the non‑default unwanted-reply-threshold to a value greater than 0; the Unbound daemon itself is not affected. Exploitation requires creating high‑complexity network conditions (enough wrong‑transaction‑ID UDP replies from an authoritative server to exceed the configured threshold), with no confidentiality or integrity impact. In managed server/VM deployments that run Unbound as a standalone resolver or do not enable this specific libunbound option, the practical risk is negligible and the issue can be safely deprioritized.", "product_ids": [ "CentOS-6:unbound-0:1.4.20-29.el6_10.1.i686", "CentOS-6:unbound-0:1.4.20-29.el6_10.1.tuxcare.els2.i686", "CentOS-6:unbound-0:1.4.20-29.el6_10.1.tuxcare.els2.x86_64", "CentOS-6:unbound-0:1.4.20-29.el6_10.1.x86_64", "CentOS-6:unbound-devel-0:1.4.20-29.el6_10.1.i686", "CentOS-6:unbound-devel-0:1.4.20-29.el6_10.1.tuxcare.els2.i686", "CentOS-6:unbound-devel-0:1.4.20-29.el6_10.1.tuxcare.els2.x86_64", "CentOS-6:unbound-devel-0:1.4.20-29.el6_10.1.x86_64", "CentOS-6:unbound-libs-0:1.4.20-29.el6_10.1.i686", "CentOS-6:unbound-libs-0:1.4.20-29.el6_10.1.tuxcare.els2.i686", "CentOS-6:unbound-libs-0:1.4.20-29.el6_10.1.tuxcare.els2.x86_64", "CentOS-6:unbound-libs-0:1.4.20-29.el6_10.1.x86_64", "CentOS-6:unbound-python-0:1.4.20-29.el6_10.1.i686", "CentOS-6:unbound-python-0:1.4.20-29.el6_10.1.tuxcare.els2.i686", "CentOS-6:unbound-python-0:1.4.20-29.el6_10.1.tuxcare.els2.x86_64", "CentOS-6:unbound-python-0:1.4.20-29.el6_10.1.x86_64" ] } ] } ] }