Medium
tar — security advisory
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.
- Products
- tar
- Affected 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, 1.27.1-2, 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, 1.28-2ubuntu1, 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, 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, 1.34+dfsg-1.2ubuntu1, 1.34+dfsg-1.2ubuntu2, 1.34+dfsg-1.3ubuntu1, 1.34+dfsg-1.4, 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, 1.35+dfsg-2, 1.35+dfsg-2~build1, 1.35+dfsg-3, 1.35+dfsg-3.1build1, 1.35+dfsg-3.1build2, 1.35+dfsg-3build1, 1.35+dfsg-3ubuntu0.1, 1.35+dfsg-3ubuntu0.2, 1.35+dfsg-3ubuntu0.3, 1.35+dfsg-3ubuntu0.4, 1.35+dfsg-4, 1.35+dfsg-4ubuntu0.1, 1.35+dfsg-4ubuntu0.2, 1.35+dfsg-4ubuntu0.3, 1.35+dfsg-4ubuntu0.4, 1.35+dfsg-5ubuntu1
- Fixed versions
- Not specified
- CVEs
- CVE-2026-18508
- Confirmed fixed CVEs
- Not specified
- Updated in this feed
- 31 Oct 2026, 01:24 UTC · Revision 1
Source evidence
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.
osv:UBUNTU-CVE-2026-18508
tar
Fixed versions: Not specified
tar
Fixed versions: Not specified
tar
Fixed versions: Not specified
tar
Fixed versions: Not specified
tar
Fixed versions: Not specified
tar
Fixed versions: Not specified
tar
Fixed versions: Not specified
tar
Fixed versions: Not specified
Complete source record
{
"id": "e581e8a24f17870abca19a3c99f33c315a1c6de4afdcf6050e402573c4277c34",
"url": "https://osv.dev/vulnerability/UBUNTU-CVE-2026-18508",
"method": "structured",
"payload": {
"kind": "advisory",
"title": "UBUNTU-CVE-2026-18508",
"summary": "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.",
"evidence": "osv:UBUNTU-CVE-2026-18508",
"products": [
{
"name": {
"value": "tar",
"evidence": "/affected/0/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "1.26+dfsg-8",
"evidence": "/affected/0/versions"
},
{
"value": "1.27-3",
"evidence": "/affected/0/versions"
},
{
"value": "1.27-4",
"evidence": "/affected/0/versions"
},
{
"value": "1.27.1-1",
"evidence": "/affected/0/versions"
},
{
"value": "1.27.1-1ubuntu0.1",
"evidence": "/affected/0/versions"
},
{
"value": "1.27.1-1ubuntu0.1+esm1",
"evidence": "/affected/0/versions"
},
{
"value": "1.27.1-1ubuntu0.1+esm2",
"evidence": "/affected/0/versions"
},
{
"value": "1.27.1-1ubuntu0.1+esm3",
"evidence": "/affected/0/versions"
},
{
"value": "1.27.1-1ubuntu0.1+esm4",
"evidence": "/affected/0/versions"
},
{
"value": "1.27.1-1ubuntu0.1+esm5",
"evidence": "/affected/0/versions"
},
{
"value": "1.27.1-1ubuntu0.1+esm6",
"evidence": "/affected/0/versions"
},
{
"value": "1.27.1-1ubuntu0.1+esm7",
"evidence": "/affected/0/versions"
}
]
},
{
"name": {
"value": "tar",
"evidence": "/affected/1/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "1.27.1-2",
"evidence": "/affected/1/versions"
},
{
"value": "1.28-2ubuntu1",
"evidence": "/affected/1/versions"
},
{
"value": "1.28-2.1",
"evidence": "/affected/1/versions"
},
{
"value": "1.28-2.1ubuntu0.1",
"evidence": "/affected/1/versions"
},
{
"value": "1.28-2.1ubuntu0.2",
"evidence": "/affected/1/versions"
},
{
"value": "1.28-2.1ubuntu0.2+esm1",
"evidence": "/affected/1/versions"
},
{
"value": "1.28-2.1ubuntu0.2+esm2",
"evidence": "/affected/1/versions"
},
{
"value": "1.28-2.1ubuntu0.2+esm3",
"evidence": "/affected/1/versions"
},
{
"value": "1.28-2.1ubuntu0.2+esm4",
"evidence": "/affected/1/versions"
},
{
"value": "1.28-2.1ubuntu0.2+esm5",
"evidence": "/affected/1/versions"
},
{
"value": "1.28-2.1ubuntu0.2+esm6",
"evidence": "/affected/1/versions"
}
]
},
{
"name": {
"value": "tar",
"evidence": "/affected/2/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "1.29b-2",
"evidence": "/affected/2/versions"
},
{
"value": "1.29b-2ubuntu0.1",
"evidence": "/affected/2/versions"
},
{
"value": "1.29b-2ubuntu0.2",
"evidence": "/affected/2/versions"
},
{
"value": "1.29b-2ubuntu0.3",
"evidence": "/affected/2/versions"
},
{
"value": "1.29b-2ubuntu0.4",
"evidence": "/affected/2/versions"
},
{
"value": "1.29b-2ubuntu0.4+esm1",
"evidence": "/affected/2/versions"
},
{
"value": "1.29b-2ubuntu0.4+esm2",
"evidence": "/affected/2/versions"
},
{
"value": "1.29b-2ubuntu0.4+esm3",
"evidence": "/affected/2/versions"
},
{
"value": "1.29b-2ubuntu0.4+esm4",
"evidence": "/affected/2/versions"
}
]
},
{
"name": {
"value": "tar",
"evidence": "/affected/3/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "1.30+dfsg-6",
"evidence": "/affected/3/versions"
},
{
"value": "1.30+dfsg-7",
"evidence": "/affected/3/versions"
},
{
"value": "1.30+dfsg-7ubuntu0.20.04.1",
"evidence": "/affected/3/versions"
},
{
"value": "1.30+dfsg-7ubuntu0.20.04.2",
"evidence": "/affected/3/versions"
},
{
"value": "1.30+dfsg-7ubuntu0.20.04.3",
"evidence": "/affected/3/versions"
},
{
"value": "1.30+dfsg-7ubuntu0.20.04.4",
"evidence": "/affected/3/versions"
},
{
"value": "1.30+dfsg-7ubuntu0.20.04.4+esm1",
"evidence": "/affected/3/versions"
},
{
"value": "1.30+dfsg-7ubuntu0.20.04.4+esm2",
"evidence": "/affected/3/versions"
},
{
"value": "1.30+dfsg-7ubuntu0.20.04.4+esm3",
"evidence": "/affected/3/versions"
}
]
},
{
"name": {
"value": "tar",
"evidence": "/affected/4/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "1.34+dfsg-1build1",
"evidence": "/affected/4/versions"
},
{
"value": "1.34+dfsg-1build2",
"evidence": "/affected/4/versions"
},
{
"value": "1.34+dfsg-1build3",
"evidence": "/affected/4/versions"
},
{
"value": "1.34+dfsg-1ubuntu0.1.22.04.1",
"evidence": "/affected/4/versions"
},
{
"value": "1.34+dfsg-1ubuntu0.1.22.04.2",
"evidence": "/affected/4/versions"
},
{
"value": "1.34+dfsg-1ubuntu0.1.22.04.3",
"evidence": "/affected/4/versions"
},
{
"value": "1.34+dfsg-1ubuntu0.1.22.04.4",
"evidence": "/affected/4/versions"
},
{
"value": "1.34+dfsg-1ubuntu0.1.22.04.5",
"evidence": "/affected/4/versions"
},
{
"value": "1.34+dfsg-1ubuntu0.1.22.04.6",
"evidence": "/affected/4/versions"
}
]
},
{
"name": {
"value": "tar",
"evidence": "/affected/5/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "1.34+dfsg-1.2ubuntu1",
"evidence": "/affected/5/versions"
},
{
"value": "1.34+dfsg-1.2ubuntu2",
"evidence": "/affected/5/versions"
},
{
"value": "1.34+dfsg-1.3ubuntu1",
"evidence": "/affected/5/versions"
},
{
"value": "1.34+dfsg-1.4",
"evidence": "/affected/5/versions"
},
{
"value": "1.35+dfsg-2~build1",
"evidence": "/affected/5/versions"
},
{
"value": "1.35+dfsg-2",
"evidence": "/affected/5/versions"
},
{
"value": "1.35+dfsg-3",
"evidence": "/affected/5/versions"
},
{
"value": "1.35+dfsg-3build1",
"evidence": "/affected/5/versions"
},
{
"value": "1.35+dfsg-3ubuntu0.1",
"evidence": "/affected/5/versions"
},
{
"value": "1.35+dfsg-3ubuntu0.2",
"evidence": "/affected/5/versions"
},
{
"value": "1.35+dfsg-3ubuntu0.3",
"evidence": "/affected/5/versions"
},
{
"value": "1.35+dfsg-3ubuntu0.4",
"evidence": "/affected/5/versions"
}
]
},
{
"name": {
"value": "tar",
"evidence": "/affected/6/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "1.35+dfsg-4",
"evidence": "/affected/6/versions"
},
{
"value": "1.35+dfsg-5ubuntu1",
"evidence": "/affected/6/versions"
}
]
},
{
"name": {
"value": "tar",
"evidence": "/affected/7/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "1.35+dfsg-3.1build1",
"evidence": "/affected/7/versions"
},
{
"value": "1.35+dfsg-3.1build2",
"evidence": "/affected/7/versions"
},
{
"value": "1.35+dfsg-4",
"evidence": "/affected/7/versions"
},
{
"value": "1.35+dfsg-4ubuntu0.1",
"evidence": "/affected/7/versions"
},
{
"value": "1.35+dfsg-4ubuntu0.2",
"evidence": "/affected/7/versions"
},
{
"value": "1.35+dfsg-4ubuntu0.3",
"evidence": "/affected/7/versions"
},
{
"value": "1.35+dfsg-4ubuntu0.4",
"evidence": "/affected/7/versions"
}
]
}
],
"severity": "medium",
"structured": {
"id": "UBUNTU-CVE-2026-18508",
"aliases": [
"UBUNTU-CVE-2026-18508"
],
"metrics": [
{
"type": "CVSS_V3",
"score": "CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N"
},
{
"type": "Ubuntu",
"score": "medium"
}
],
"affected": [
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "tar",
"purl": "pkg:deb/ubuntu/tar?arch=source&distro=esm-infra-legacy%2Ftrusty",
"ecosystem": "Ubuntu:Pro:14.04:LTS"
},
"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"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-18508.json"
},
"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"
}
]
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "tar",
"purl": "pkg:deb/ubuntu/tar?arch=source&distro=esm-infra-legacy%2Fxenial",
"ecosystem": "Ubuntu:Pro:16.04:LTS"
},
"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"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-18508.json"
},
"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"
}
]
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "tar",
"purl": "pkg:deb/ubuntu/tar?arch=source&distro=esm-infra%2Fbionic",
"ecosystem": "Ubuntu:Pro:18.04:LTS"
},
"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"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-18508.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "tar",
"binary_version": "1.29b-2ubuntu0.4+esm4"
},
{
"binary_name": "tar-scripts",
"binary_version": "1.29b-2ubuntu0.4+esm4"
}
]
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "tar",
"purl": "pkg:deb/ubuntu/tar?arch=source&distro=esm-infra%2Ffocal",
"ecosystem": "Ubuntu:Pro:20.04:LTS"
},
"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"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-18508.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "tar",
"binary_version": "1.30+dfsg-7ubuntu0.20.04.4+esm3"
},
{
"binary_name": "tar-scripts",
"binary_version": "1.30+dfsg-7ubuntu0.20.04.4+esm3"
}
]
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "tar",
"purl": "pkg:deb/ubuntu/tar?arch=source&distro=jammy",
"ecosystem": "Ubuntu:22.04:LTS"
},
"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"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-18508.json"
},
"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"
}
]
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "tar",
"purl": "pkg:deb/ubuntu/tar?arch=source&distro=noble",
"ecosystem": "Ubuntu:24.04:LTS"
},
"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"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-18508.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "tar",
"binary_version": "1.35+dfsg-3ubuntu0.4"
},
{
"binary_name": "tar-scripts",
"binary_version": "1.35+dfsg-3ubuntu0.4"
}
]
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "tar",
"purl": "pkg:deb/ubuntu/tar?arch=source&distro=stonking",
"ecosystem": "Ubuntu:26.10"
},
"versions": [
"1.35+dfsg-4",
"1.35+dfsg-5ubuntu1"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-18508.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "tar",
"binary_version": "1.35+dfsg-5ubuntu1"
},
{
"binary_name": "tar-scripts",
"binary_version": "1.35+dfsg-5ubuntu1"
}
]
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "tar",
"purl": "pkg:deb/ubuntu/tar?arch=source&distro=resolute",
"ecosystem": "Ubuntu:26.04:LTS"
},
"versions": [
"1.35+dfsg-3.1build1",
"1.35+dfsg-3.1build2",
"1.35+dfsg-4",
"1.35+dfsg-4ubuntu0.1",
"1.35+dfsg-4ubuntu0.2",
"1.35+dfsg-4ubuntu0.3",
"1.35+dfsg-4ubuntu0.4"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-18508.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "tar",
"binary_version": "1.35+dfsg-4ubuntu0.4"
},
{
"binary_name": "tar-scripts",
"binary_version": "1.35+dfsg-4ubuntu0.4"
}
]
}
}
],
"modified": "2026-10-17T12:56:47.255674368Z",
"provider": "osv",
"upstream": [
"CVE-2026-18508"
],
"references": [
"https://ubuntu.com/security/CVE-2026-18508",
"https://www.cve.org/CVERecord?id=CVE-2026-18508",
"https://access.redhat.com/security/cve/CVE-2026-18508"
]
},
"related_cves": [
{
"value": "CVE-2026-18508",
"evidence": "/upstream"
}
],
"security_relevant": true,
"severity_evidence": "/severity/0/score"
},
"source_id": "core-osv",
"document_id": 356256,
"published_at": "2026-08-03T16:16:00+00:00"
}