{ "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/ubuntu16.04els/vex/2026/cve-2026-18477-els_os-ubuntu16_04els.json" } ], "tracking": { "current_release_date": "2026-08-26T16:43:32Z", "generator": { "date": "2026-08-26T16:43:32Z", "engine": { "name": "pyCSAF" } }, "id": "CVE-2026-18477-ELS_OS-UBUNTU16.04ELS", "initial_release_date": "2026-08-03T17:16:00Z", "revision_history": [ { "date": "2026-08-03T17:16:00Z", "number": "1", "summary": "Initial version" }, { "date": "2026-08-26T12:56:24Z", "number": "2", "summary": "Official Publication" }, { "date": "2026-08-26T16:43:32Z", "number": "3", "summary": "Update document" } ], "status": "final", "version": "3" }, "title": "Security update on CVE-2026-18477" }, "product_tree": { "branches": [ { "branches": [ { "branches": [ { "category": "product_name", "name": "Ubuntu 16.04", "product": { "name": "Ubuntu 16.04", "product_id": "Ubuntu-16", "product_identification_helper": { "cpe": "cpe:2.3:o:canonical:ubuntu_linux:16.04:*:*:*:lts:*:*:*" } } } ], "category": "product_family", "name": "Ubuntu" }, { "branches": [ { "category": "product_version", "name": "tar-scripts-0:1.28-2.1ubuntu0.2.amd64", "product": { "name": "tar-scripts-0:1.28-2.1ubuntu0.2.amd64", "product_id": "tar-scripts-0:1.28-2.1ubuntu0.2.amd64", "product_identification_helper": { "purl": "pkg:deb/ubuntu/tar-scripts@1.28-2.1ubuntu0.2?arch=amd64" } } }, { "category": "product_version", "name": "tar-0:1.28-2.1ubuntu0.2.amd64", "product": { "name": "tar-0:1.28-2.1ubuntu0.2.amd64", "product_id": "tar-0:1.28-2.1ubuntu0.2.amd64", "product_identification_helper": { "purl": "pkg:deb/ubuntu/tar@1.28-2.1ubuntu0.2?arch=amd64" } } } ], "category": "architecture", "name": "amd64" } ], "category": "vendor", "name": "Canonical Ltd." }, { "branches": [ { "branches": [ { "category": "product_version", "name": "tar-scripts-0:1.28-2.1ubuntu0.2+tuxcare.els2.amd64", "product": { "name": "tar-scripts-0:1.28-2.1ubuntu0.2+tuxcare.els2.amd64", "product_id": "tar-scripts-0:1.28-2.1ubuntu0.2+tuxcare.els2.amd64", "product_identification_helper": { "purl": "pkg:deb/cloudlinux/tar-scripts@1.28-2.1ubuntu0.2%2Btuxcare.els2?arch=amd64" } } }, { "category": "product_version", "name": "tar-scripts-0:1.28-2.1ubuntu0.2+tuxcare.els1.amd64", "product": { "name": "tar-scripts-0:1.28-2.1ubuntu0.2+tuxcare.els1.amd64", "product_id": "tar-scripts-0:1.28-2.1ubuntu0.2+tuxcare.els1.amd64", "product_identification_helper": { "purl": "pkg:deb/cloudlinux/tar-scripts@1.28-2.1ubuntu0.2%2Btuxcare.els1?arch=amd64" } } }, { "category": "product_version", "name": "tar-0:1.28-2.1ubuntu0.2+tuxcare.els2.amd64", "product": { "name": "tar-0:1.28-2.1ubuntu0.2+tuxcare.els2.amd64", "product_id": "tar-0:1.28-2.1ubuntu0.2+tuxcare.els2.amd64", "product_identification_helper": { "purl": "pkg:deb/cloudlinux/tar@1.28-2.1ubuntu0.2%2Btuxcare.els2?arch=amd64" } } }, { "category": "product_version", "name": "tar-0:1.28-2.1ubuntu0.2+tuxcare.els1.amd64", "product": { "name": "tar-0:1.28-2.1ubuntu0.2+tuxcare.els1.amd64", "product_id": "tar-0:1.28-2.1ubuntu0.2+tuxcare.els1.amd64", "product_identification_helper": { "purl": "pkg:deb/cloudlinux/tar@1.28-2.1ubuntu0.2%2Btuxcare.els1?arch=amd64" } } } ], "category": "architecture", "name": "amd64" } ], "category": "vendor", "name": "CloudLinux" } ], "relationships": [ { "category": "default_component_of", "full_product_name": { "name": "tar-scripts-0:1.28-2.1ubuntu0.2+tuxcare.els2.amd64 as a component of Ubuntu 16.04", "product_id": "Ubuntu-16:tar-scripts-0:1.28-2.1ubuntu0.2+tuxcare.els2.amd64" }, "product_reference": "tar-scripts-0:1.28-2.1ubuntu0.2+tuxcare.els2.amd64", "relates_to_product_reference": "Ubuntu-16" }, { "category": "default_component_of", "full_product_name": { "name": "tar-scripts-0:1.28-2.1ubuntu0.2+tuxcare.els1.amd64 as a component of Ubuntu 16.04", "product_id": "Ubuntu-16:tar-scripts-0:1.28-2.1ubuntu0.2+tuxcare.els1.amd64" }, "product_reference": "tar-scripts-0:1.28-2.1ubuntu0.2+tuxcare.els1.amd64", "relates_to_product_reference": "Ubuntu-16" }, { "category": "default_component_of", "full_product_name": { "name": "tar-0:1.28-2.1ubuntu0.2+tuxcare.els2.amd64 as a component of Ubuntu 16.04", "product_id": "Ubuntu-16:tar-0:1.28-2.1ubuntu0.2+tuxcare.els2.amd64" }, "product_reference": "tar-0:1.28-2.1ubuntu0.2+tuxcare.els2.amd64", "relates_to_product_reference": "Ubuntu-16" }, { "category": "default_component_of", "full_product_name": { "name": "tar-0:1.28-2.1ubuntu0.2+tuxcare.els1.amd64 as a component of Ubuntu 16.04", "product_id": "Ubuntu-16:tar-0:1.28-2.1ubuntu0.2+tuxcare.els1.amd64" }, "product_reference": "tar-0:1.28-2.1ubuntu0.2+tuxcare.els1.amd64", "relates_to_product_reference": "Ubuntu-16" }, { "category": "default_component_of", "full_product_name": { "name": "tar-scripts-0:1.28-2.1ubuntu0.2.amd64 as a component of Ubuntu 16.04", "product_id": "Ubuntu-16:tar-scripts-0:1.28-2.1ubuntu0.2.amd64" }, "product_reference": "tar-scripts-0:1.28-2.1ubuntu0.2.amd64", "relates_to_product_reference": "Ubuntu-16" }, { "category": "default_component_of", "full_product_name": { "name": "tar-0:1.28-2.1ubuntu0.2.amd64 as a component of Ubuntu 16.04", "product_id": "Ubuntu-16:tar-0:1.28-2.1ubuntu0.2.amd64" }, "product_reference": "tar-0:1.28-2.1ubuntu0.2.amd64", "relates_to_product_reference": "Ubuntu-16" } ] }, "vulnerabilities": [ { "cve": "CVE-2026-18477", "cwe": { "id": "CWE-367", "name": "Time-of-check Time-of-use (TOCTOU) Race Condition" }, "notes": [ { "category": "description", "text": "A TOCTOU (Time-of-Check Time-of-Use) vulnerability in GNU tar's incremental dumpdir 'X' rename handling allows a local attacker with write access to a directory being backed up to influence the restore process if the attacker has access to the system where the restore is being performed. During restoration, files or directories may be created, renamed or overwritten outside the intended extraction directory. This could lead to unauthorized file modification or, in some cases, privilege escalation. Exploitation does not require the attacker to modify or craft the archive, and standard backup and restore workflows—including extracting into a newly created directory without using the -P option do not mitigate the issue.", "title": "Vulnerability description" } ], "product_status": { "known_affected": [ "Ubuntu-16:tar-0:1.28-2.1ubuntu0.2+tuxcare.els1.amd64", "Ubuntu-16:tar-0:1.28-2.1ubuntu0.2+tuxcare.els2.amd64", "Ubuntu-16:tar-0:1.28-2.1ubuntu0.2.amd64", "Ubuntu-16:tar-scripts-0:1.28-2.1ubuntu0.2+tuxcare.els1.amd64", "Ubuntu-16:tar-scripts-0:1.28-2.1ubuntu0.2+tuxcare.els2.amd64", "Ubuntu-16:tar-scripts-0:1.28-2.1ubuntu0.2.amd64" ] }, "references": [ { "category": "self", "summary": "Canonical URL", "url": "https://cve.tuxcare.com/els/cve/CVE-2026-18477" }, { "category": "external", "summary": "https://access.redhat.com/errata/RHSA-2026:49361", "url": "https://access.redhat.com/errata/RHSA-2026:49361" }, { "category": "external", "summary": "https://access.redhat.com/security/cve/CVE-2026-18477", "url": "https://access.redhat.com/security/cve/CVE-2026-18477" }, { "category": "external", "summary": "https://bugzilla.redhat.com/show_bug.cgi?id=2509735", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2509735" } ], "release_date": "2026-08-03T17:16:00Z", "remediations": [ { "category": "no_fix_planned", "date": "2026-08-26T14:17:23.247178Z", "details": "This flaw is only reachable during GNU tar’s listed-incremental restore path (dumpdir “X” rename handling) and requires a user‑initiated extraction, so the exposure window is narrowly limited to restore operations rather than normal runtime. Successful exploitation further demands that an attacker already has local write access to the directory at backup time and concurrent access on the system performing the restore, plus winning a TOCTOU race—conditions that make real‑world abuse in managed VM/server deployments unlikely. Because the impact is confined to integrity (no confidentiality or availability effect), this can be safely deprioritized relative to vulnerabilities that permit remote compromise or broader impact.", "product_ids": [ "Ubuntu-16:tar-0:1.28-2.1ubuntu0.2+tuxcare.els1.amd64", "Ubuntu-16:tar-0:1.28-2.1ubuntu0.2+tuxcare.els2.amd64", "Ubuntu-16:tar-0:1.28-2.1ubuntu0.2.amd64", "Ubuntu-16:tar-scripts-0:1.28-2.1ubuntu0.2+tuxcare.els1.amd64", "Ubuntu-16:tar-scripts-0:1.28-2.1ubuntu0.2+tuxcare.els2.amd64", "Ubuntu-16:tar-scripts-0:1.28-2.1ubuntu0.2.amd64" ] } ] } ] }