{"id":"UBUNTU-CVE-2026-18508","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.","modified":"2026-08-26T01:21:32.394095801Z","published":"2026-08-03T16:16:00Z","upstream":["CVE-2026-18508"],"references":[{"type":"REPORT","url":"https://ubuntu.com/security/CVE-2026-18508"},{"type":"REPORT","url":"https://www.cve.org/CVERecord?id=CVE-2026-18508"},{"type":"REPORT","url":"https://access.redhat.com/security/cve/CVE-2026-18508"}],"affected":[{"package":{"name":"tar","ecosystem":"Ubuntu:Pro:14.04:LTS","purl":"pkg:deb/ubuntu/tar?arch=source&distro=esm-infra-legacy%2Ftrusty"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.26+dfsg-8","1.27-3","1.27-4","1.27.1-1","1.27.1-1ubuntu0.1","1.27.1-1ubuntu0.1+esm1","1.27.1-1ubuntu0.1+esm2","1.27.1-1ubuntu0.1+esm3","1.27.1-1ubuntu0.1+esm4","1.27.1-1ubuntu0.1+esm5","1.27.1-1ubuntu0.1+esm6","1.27.1-1ubuntu0.1+esm7"],"ecosystem_specific":{"binaries":[{"binary_name":"tar","binary_version":"1.27.1-1ubuntu0.1+esm7"},{"binary_name":"tar-scripts","binary_version":"1.27.1-1ubuntu0.1+esm7"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-18508.json"}},{"package":{"name":"tar","ecosystem":"Ubuntu:Pro:16.04:LTS","purl":"pkg:deb/ubuntu/tar?arch=source&distro=esm-infra-legacy%2Fxenial"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.27.1-2","1.28-2ubuntu1","1.28-2.1","1.28-2.1ubuntu0.1","1.28-2.1ubuntu0.2","1.28-2.1ubuntu0.2+esm1","1.28-2.1ubuntu0.2+esm2","1.28-2.1ubuntu0.2+esm3","1.28-2.1ubuntu0.2+esm4","1.28-2.1ubuntu0.2+esm5","1.28-2.1ubuntu0.2+esm6"],"ecosystem_specific":{"binaries":[{"binary_name":"tar","binary_version":"1.28-2.1ubuntu0.2+esm6"},{"binary_name":"tar-scripts","binary_version":"1.28-2.1ubuntu0.2+esm6"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-18508.json"}},{"package":{"name":"tar","ecosystem":"Ubuntu:Pro:18.04:LTS","purl":"pkg:deb/ubuntu/tar?arch=source&distro=esm-infra%2Fbionic"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.29b-2","1.29b-2ubuntu0.1","1.29b-2ubuntu0.2","1.29b-2ubuntu0.3","1.29b-2ubuntu0.4","1.29b-2ubuntu0.4+esm1","1.29b-2ubuntu0.4+esm2","1.29b-2ubuntu0.4+esm3","1.29b-2ubuntu0.4+esm4"],"ecosystem_specific":{"binaries":[{"binary_name":"tar","binary_version":"1.29b-2ubuntu0.4+esm4"},{"binary_name":"tar-scripts","binary_version":"1.29b-2ubuntu0.4+esm4"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-18508.json"}},{"package":{"name":"tar","ecosystem":"Ubuntu:Pro:20.04:LTS","purl":"pkg:deb/ubuntu/tar?arch=source&distro=esm-infra%2Ffocal"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.30+dfsg-6","1.30+dfsg-7","1.30+dfsg-7ubuntu0.20.04.1","1.30+dfsg-7ubuntu0.20.04.2","1.30+dfsg-7ubuntu0.20.04.3","1.30+dfsg-7ubuntu0.20.04.4","1.30+dfsg-7ubuntu0.20.04.4+esm1","1.30+dfsg-7ubuntu0.20.04.4+esm2","1.30+dfsg-7ubuntu0.20.04.4+esm3"],"ecosystem_specific":{"binaries":[{"binary_version":"1.30+dfsg-7ubuntu0.20.04.4+esm3","binary_name":"tar"},{"binary_name":"tar-scripts","binary_version":"1.30+dfsg-7ubuntu0.20.04.4+esm3"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-18508.json"}},{"package":{"name":"tar","ecosystem":"Ubuntu:22.04:LTS","purl":"pkg:deb/ubuntu/tar?arch=source&distro=jammy"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.34+dfsg-1build1","1.34+dfsg-1build2","1.34+dfsg-1build3","1.34+dfsg-1ubuntu0.1.22.04.1","1.34+dfsg-1ubuntu0.1.22.04.2","1.34+dfsg-1ubuntu0.1.22.04.3","1.34+dfsg-1ubuntu0.1.22.04.4","1.34+dfsg-1ubuntu0.1.22.04.5","1.34+dfsg-1ubuntu0.1.22.04.6"],"ecosystem_specific":{"binaries":[{"binary_name":"tar","binary_version":"1.34+dfsg-1ubuntu0.1.22.04.6"},{"binary_name":"tar-scripts","binary_version":"1.34+dfsg-1ubuntu0.1.22.04.6"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-18508.json"}},{"package":{"name":"tar","ecosystem":"Ubuntu:24.04:LTS","purl":"pkg:deb/ubuntu/tar?arch=source&distro=noble"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.34+dfsg-1.2ubuntu1","1.34+dfsg-1.2ubuntu2","1.34+dfsg-1.3ubuntu1","1.34+dfsg-1.4","1.35+dfsg-2~build1","1.35+dfsg-2","1.35+dfsg-3","1.35+dfsg-3build1","1.35+dfsg-3ubuntu0.1","1.35+dfsg-3ubuntu0.2","1.35+dfsg-3ubuntu0.3","1.35+dfsg-3ubuntu0.4"],"ecosystem_specific":{"binaries":[{"binary_name":"tar","binary_version":"1.35+dfsg-3ubuntu0.4"},{"binary_version":"1.35+dfsg-3ubuntu0.4","binary_name":"tar-scripts"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-18508.json"}},{"package":{"name":"tar","ecosystem":"Ubuntu:26.04:LTS","purl":"pkg:deb/ubuntu/tar?arch=source&distro=resolute"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}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