CVE-2026-18508

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{"acknowledgement": "This issue was discovered by Pavel Cahyna (Red Hat).", "bugzilla": {"description": "tar: tar: --one-top-level hardlink targets not confined to top-level directory enabling arbitrary file overwrite", "id": "2509843", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2509843"}, "csaw": false, "cvss3": {"cvss3_base_score": "4.4", "cvss3_scoring_vector": "CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N", "status": "draft"}, "cwe": "CWE-59", "details": ["A flaw was found in GNU tar. When extracting an archive with the --one-top-level option, hardlink targets are not confined to the designated top-level directory and may resolve relative to the extraction working directory. A crafted archive can create hardlinks that escape the intended boundary and, when combined with a preexisting symbolic link under the working directory, may allow writing outside that boundary during a single extraction."], "mitigation": {"lang": "en:us", "value": "Do not use --one-top-level as the sole confinement mechanism when extracting untrusted archives. Prefer extracting as an unprivileged user into a freshly created empty directory after changing into that directory (mkdir and cd), avoid extracting as root from sensitive working directories such as /, and follow the GNU tar security guidance for untrusted archives."}, "name": "CVE-2026-18508", "package_state": [{"cpe": "cpe:/o:redhat:enterprise_linux:10", "fix_state": "Fix deferred", "package_name": "tar", "product_name": "Red Hat Enterprise Linux 10"}, {"cpe": "cpe:/o:redhat:enterprise_linux:6", "fix_state": "Out of support scope", "package_name": "tar", "product_name": "Red Hat Enterprise Linux 6"}, {"cpe": "cpe:/o:redhat:enterprise_linux:7", "fix_state": "Out of support scope", "package_name": "tar", "product_name": "Red Hat Enterprise Linux 7"}, {"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Fix deferred", "package_name": "tar", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Fix deferred", "package_name": "tar", "product_name": "Red Hat Enterprise Linux 9"}, {"cpe": "cpe:/a:redhat:hummingbird:1", "fix_state": "Not affected", "package_name": "aardvark-dns", "product_name": "Red Hat Hardened Images"}, {"cpe": "cpe:/a:redhat:hummingbird:1", "fix_state": "Not affected", "package_name": "chunkah", "product_name": "Red Hat Hardened Images"}, {"cpe": "cpe:/a:redhat:hummingbird:1", "fix_state": "Not affected", "package_name": "grafana12.4", "product_name": "Red Hat Hardened Images"}, {"cpe": "cpe:/a:redhat:hummingbird:1", "fix_state": "Not affected", "package_name": "grafana13.1", "product_name": "Red Hat Hardened Images"}, {"cpe": "cpe:/a:redhat:hummingbird:1", "fix_state": "Not affected", "package_name": "netavark", "product_name": "Red Hat Hardened Images"}, {"cpe": "cpe:/a:redhat:hummingbird:1", "fix_state": "Not affected", "package_name": "nodejs26", "product_name": "Red Hat Hardened Images"}, {"cpe": "cpe:/a:redhat:hummingbird:1", "fix_state": "Not affected", "package_name": "python-cryptography", "product_name": "Red Hat Hardened Images"}, {"cpe": "cpe:/a:redhat:hummingbird:1", "fix_state": "Not affected", "package_name": "rust", "product_name": "Red Hat Hardened Images"}, {"cpe": "cpe:/a:redhat:hummingbird:1", "fix_state": "Not affected", "package_name": "rust-rpm-sequoia", "product_name": "Red Hat Hardened Images"}, {"cpe": "cpe:/a:redhat:hummingbird:1", "fix_state": "Affected", "package_name": "tar", "product_name": "Red Hat Hardened Images"}, {"cpe": "cpe:/a:redhat:hummingbird:1", "fix_state": "Not affected", "package_name": "yarnpkg", "product_name": "Red Hat Hardened Images"}, {"cpe": "cpe:/a:redhat:openshift:4", "fix_state": "Fix deferred", "package_name": "rhcos", "product_name": "Red Hat OpenShift Container Platform 4"}], "public_date": "2026-07-31T00:00:00Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2026-18508\nhttps://nvd.nist.gov/vuln/detail/CVE-2026-18508"], "statement": "Red Hat Enterprise Linux is affected. This issue only applies when the --one-top-level option is used to extract an untrusted archive. Default tar extraction without --one-top-level is not impacted by this specific boundary failure. Users should avoid using --one-top-level as the sole confinement mechanism for untrusted archives until fixed packages are available.", "threat_severity": "Moderate"}

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