{ "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-2026-35501-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-2026-35501-ELS_OS-CENTOS6ELS", "initial_release_date": "2026-10-21T09:17:00Z", "revision_history": [ { "date": "2026-10-21T09:17:00Z", "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-2026-35501", "cwe": { "id": "CWE-354", "name": "Improper Validation of Integrity Check Value" }, "notes": [ { "category": "description", "text": "When NLnet Labs Unbound 1.0.1 up to and including version 1.26.1 is configured with both a root trust anchor and an additional 'trust-anchor:' for an island-of-security zone whose parent is provably insecure under the root chain, a malicious actor with a forged NSEC reply with the SOA bit cleared can trick Unbound to treat the configured trust island as insecure. This happens because the DNSSEC validator in Unbound accepts and caches the NSEC insecure response bypassing the RRSIG validation that the validator was supposed to do. The acceptance of the NSEC record at the trust anchor apex was allowed due to and old fix for type DS and NSEC queries from clients when trust anchor for that name existed.", "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-2026-35501" }, { "category": "external", "summary": "https://www.nlnetlabs.nl/downloads/unbound/CVE-2026-35501.txt", "url": "https://www.nlnetlabs.nl/downloads/unbound/CVE-2026-35501.txt" } ], "release_date": "2026-10-21T09:17:00Z", "remediations": [ { "category": "no_fix_planned", "date": "2026-10-24T11:23:20.926448Z", "details": "This issue only manifests under a narrow, non-default configuration: Unbound must be set up with both the root trust anchor and an explicit trust-anchor for an “island-of-security” zone whose parent is provably insecure. Exploitation further requires an attacker to inject a precisely forged NSEC response with the SOA bit cleared to race or intercept resolver traffic, which is a high‑complexity network attack with no user interaction. The result is limited to downgrading DNSSEC validation for that specific island (no code execution or data disclosure), so in centrally managed enterprise resolver deployments it is reasonable to deprioritize.", "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" ] } ] } ] }