{ "document": { "aggregate_severity": { "text": "Medium" }, "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/ubuntu18.04els/vex/2021/cve-2021-3672-els_os-ubuntu18_04els.json" } ], "tracking": { "current_release_date": "2026-08-25T13:39:52Z", "generator": { "date": "2026-08-25T13:39:52Z", "engine": { "name": "pyCSAF" } }, "id": "CVE-2021-3672-ELS_OS-UBUNTU18.04ELS", "initial_release_date": "2021-11-23T19:15:00Z", "revision_history": [ { "date": "2021-11-23T19:15:00Z", "number": "1", "summary": "Initial version" }, { "date": "2026-08-25T13:39:52Z", "number": "2", "summary": "Official Publication" } ], "status": "final", "version": "2" }, "title": "Security update on CVE-2021-3672" }, "product_tree": { "branches": [ { "branches": [ { "branches": [ { "category": "product_name", "name": "Ubuntu 18.04", "product": { "name": "Ubuntu 18.04", "product_id": "Ubuntu-18", "product_identification_helper": { "cpe": "cpe:2.3:o:canonical:ubuntu_linux:18.04:*:*:*:lts:*:*:*" } } } ], "category": "product_family", "name": "Ubuntu" }, { "branches": [ { "category": "product_version", "name": "libc-ares-dev-0:1.14.0-1ubuntu0.2.amd64", "product": { "name": "libc-ares-dev-0:1.14.0-1ubuntu0.2.amd64", "product_id": "libc-ares-dev-0:1.14.0-1ubuntu0.2.amd64", "product_identification_helper": { "purl": "pkg:deb/ubuntu/libc-ares-dev@1.14.0-1ubuntu0.2?arch=amd64" } } }, { "category": "product_version", "name": "libc-ares2-0:1.14.0-1ubuntu0.2.amd64", "product": { "name": "libc-ares2-0:1.14.0-1ubuntu0.2.amd64", "product_id": "libc-ares2-0:1.14.0-1ubuntu0.2.amd64", "product_identification_helper": { "purl": "pkg:deb/ubuntu/libc-ares2@1.14.0-1ubuntu0.2?arch=amd64" } } } ], "category": "architecture", "name": "amd64" } ], "category": "vendor", "name": "Canonical Ltd." }, { "branches": [ { "branches": [ { "category": "product_version", "name": "libc-ares-dev-0:1.14.0-1ubuntu0.2+tuxcare.els1.amd64", "product": { "name": "libc-ares-dev-0:1.14.0-1ubuntu0.2+tuxcare.els1.amd64", "product_id": "libc-ares-dev-0:1.14.0-1ubuntu0.2+tuxcare.els1.amd64", "product_identification_helper": { "purl": "pkg:deb/cloudlinux/libc-ares-dev@1.14.0-1ubuntu0.2%2Btuxcare.els1?arch=amd64" } } }, { "category": "product_version", "name": "libc-ares2-0:1.14.0-1ubuntu0.2+tuxcare.els1.amd64", "product": { "name": "libc-ares2-0:1.14.0-1ubuntu0.2+tuxcare.els1.amd64", "product_id": "libc-ares2-0:1.14.0-1ubuntu0.2+tuxcare.els1.amd64", "product_identification_helper": { "purl": "pkg:deb/cloudlinux/libc-ares2@1.14.0-1ubuntu0.2%2Btuxcare.els1?arch=amd64" } } } ], "category": "architecture", "name": "amd64" } ], "category": "vendor", "name": "CloudLinux" } ], "relationships": [ { "category": "default_component_of", "full_product_name": { "name": "libc-ares-dev-0:1.14.0-1ubuntu0.2+tuxcare.els1.amd64 as a component of Ubuntu 18.04", "product_id": "Ubuntu-18:libc-ares-dev-0:1.14.0-1ubuntu0.2+tuxcare.els1.amd64" }, "product_reference": "libc-ares-dev-0:1.14.0-1ubuntu0.2+tuxcare.els1.amd64", "relates_to_product_reference": "Ubuntu-18" }, { "category": "default_component_of", "full_product_name": { "name": "libc-ares-dev-0:1.14.0-1ubuntu0.2.amd64 as a component of Ubuntu 18.04", "product_id": "Ubuntu-18:libc-ares-dev-0:1.14.0-1ubuntu0.2.amd64" }, "product_reference": "libc-ares-dev-0:1.14.0-1ubuntu0.2.amd64", "relates_to_product_reference": "Ubuntu-18" }, { "category": "default_component_of", "full_product_name": { "name": "libc-ares2-0:1.14.0-1ubuntu0.2+tuxcare.els1.amd64 as a component of Ubuntu 18.04", "product_id": "Ubuntu-18:libc-ares2-0:1.14.0-1ubuntu0.2+tuxcare.els1.amd64" }, "product_reference": "libc-ares2-0:1.14.0-1ubuntu0.2+tuxcare.els1.amd64", "relates_to_product_reference": "Ubuntu-18" }, { "category": "default_component_of", "full_product_name": { "name": "libc-ares2-0:1.14.0-1ubuntu0.2.amd64 as a component of Ubuntu 18.04", "product_id": "Ubuntu-18:libc-ares2-0:1.14.0-1ubuntu0.2.amd64" }, "product_reference": "libc-ares2-0:1.14.0-1ubuntu0.2.amd64", "relates_to_product_reference": "Ubuntu-18" } ] }, "vulnerabilities": [ { "cve": "CVE-2021-3672", "cwe": { "id": "CWE-79", "name": "Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')" }, "notes": [ { "category": "description", "text": "A flaw was found in c-ares library, where a missing input validation check of host names returned by DNS (Domain Name Servers) can lead to output of wrong hostnames which might potentially lead to Domain Hijacking. The highest threat from this vulnerability is to confidentiality and integrity as well as system availability.", "title": "Vulnerability description" }, { "category": "general", "text": "The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.", "title": "CVSS score applicability" } ], "product_status": { "known_affected": [ "Ubuntu-18:libc-ares-dev-0:1.14.0-1ubuntu0.2+tuxcare.els1.amd64", "Ubuntu-18:libc-ares-dev-0:1.14.0-1ubuntu0.2.amd64", "Ubuntu-18:libc-ares2-0:1.14.0-1ubuntu0.2+tuxcare.els1.amd64", "Ubuntu-18:libc-ares2-0:1.14.0-1ubuntu0.2.amd64" ] }, "references": [ { "category": "self", "summary": "Canonical URL", "url": "https://cve.tuxcare.com/els/cve/CVE-2021-3672" }, { "category": "external", "summary": "https://bugzilla.redhat.com/show_bug.cgi?id=1988342", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=1988342" }, { "category": "external", "summary": "https://c-ares.haxx.se/adv_20210810.html", "url": "https://c-ares.haxx.se/adv_20210810.html" }, { "category": "external", "summary": "https://cert-portal.siemens.com/productcert/pdf/ssa-389290.pdf", "url": "https://cert-portal.siemens.com/productcert/pdf/ssa-389290.pdf" }, { "category": "external", "summary": "https://security.gentoo.org/glsa/202401-02", "url": "https://security.gentoo.org/glsa/202401-02" }, { "category": "external", "summary": "https://www.oracle.com/security-alerts/cpujul2022.html", "url": "https://www.oracle.com/security-alerts/cpujul2022.html" } ], "release_date": "2021-11-23T19:15:00Z", "remediations": [ { "category": "no_fix_planned", "date": "2026-08-18T14:37:35.392984Z", "details": "c-ares 1.0.0–1.17.1 can return an incorrect hostname when a DNS server supplies a specially crafted name (for example, with an embedded NUL), affecting only applications that use c-ares directly and not systems relying solely on the OS resolver; it does not provide code execution and has only low confidentiality, integrity, and availability impact. Exploitation requires an attacker to control or tamper with upstream DNS responses to that application, a high‑complexity precondition that is atypical for centrally managed server/VM environments. The flaw was fixed in c-ares 1.17.2 on August 10, 2021, so only legacy builds are exposed; given the narrow scope and preconditions, this CVE can be safely deprioritized.", "product_ids": [ "Ubuntu-18:libc-ares-dev-0:1.14.0-1ubuntu0.2+tuxcare.els1.amd64", "Ubuntu-18:libc-ares-dev-0:1.14.0-1ubuntu0.2.amd64", "Ubuntu-18:libc-ares2-0:1.14.0-1ubuntu0.2+tuxcare.els1.amd64", "Ubuntu-18:libc-ares2-0:1.14.0-1ubuntu0.2.amd64" ] } ], "scores": [ { "cvss_v2": { "accessComplexity": "MEDIUM", "accessVector": "NETWORK", "authentication": "NONE", "availabilityImpact": "PARTIAL", "baseScore": 6.8, "baseSeverity": "MEDIUM", "confidentialityImpact": "PARTIAL", "integrityImpact": "PARTIAL", "vectorString": "AV:N/AC:M/Au:N/C:P/I:P/A:P", "version": "2.0" }, "cvss_v3": { "attackComplexity": "HIGH", "attackVector": "NETWORK", "availabilityImpact": "LOW", "baseScore": 5.6, "baseSeverity": "MEDIUM", "confidentialityImpact": "LOW", "integrityImpact": "LOW", "privilegesRequired": "NONE", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:L", "version": "3.1" }, "products": [ "Ubuntu-18:libc-ares-dev-0:1.14.0-1ubuntu0.2+tuxcare.els1.amd64", "Ubuntu-18:libc-ares-dev-0:1.14.0-1ubuntu0.2.amd64", "Ubuntu-18:libc-ares2-0:1.14.0-1ubuntu0.2+tuxcare.els1.amd64", "Ubuntu-18:libc-ares2-0:1.14.0-1ubuntu0.2.amd64" ] } ], "threats": [ { "category": "impact", "details": "Moderate" } ] } ] }