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Back to active CVEs
Medium · CVSS 4.4CVE-2026-18508

Tar: tar: --one-top-level hardlink targets not confined to top-level directory enabling arbitrary file overwriteCVE-2026-18508

Answer in brief

CVE-2026-18508 records a Medium severity (CVSS 4.4) vulnerability in Tar: tar: --one-top-level hardlink targets not confined to top-level directory enabling arbitrary file overwrite. The current sources do not mark it as known exploited. The current feed maps Red Hat/openshift/ose-rhel-coreos-8 (generic), Red Hat/openshift/ose-rhel-coreos-9 (generic). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Aug 3, 2026Updated Nov 2, 2026Source checked Nov 4, 2026First seen by HOL Aug 3, 2026Material review Nov 2, 2026
Upstream Advisory

Record context

Vulnerability class
Path Traversal
EPSS
Not reported
CWE IDs
CWE-59
Source
CVE List V5
Source checked
Nov 4, 2026
References
8 linked sources
Open source record

Key facts

Risk
Medium · CVSS 4.4
Exploitation
Not marked as known exploited
Affected software
7 mapped packages or products
Fix availability
Not reported

Why this deserves its current priority

CVSS is 4.4. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps Red Hat/openshift/ose-rhel-coreos-8 (generic), Red Hat/openshift/ose-rhel-coreos-9 (generic). Check affected ranges and fixed versions before updating.

Affected products and reported versions
ProductAffected versionsFixed versions
cpe:2.3:a:gnu:tar:1.35:*:*:*:*:*:*:*Not reportedNot reported
cpe:2.3:a:redhat:openshift_container_platform:4.0:*:*:*:*:*:*:*Not reportedNot reported
cpe:2.3:o:redhat:enterprise_linux:10.0:*:*:*:*:*:*:*Not reportedNot reported
cpe:2.3:o:redhat:enterprise_linux:8.0:*:*:*:*:*:*:*Not reportedNot reported
cpe:2.3:o:redhat:enterprise_linux:9.0:*:*:*:*:*:*:*Not reportedNot reported
Mapped affected packages and fixed versions
PackageAffected rangeFixed version
Red Hat/openshift/ose-rhel-coreos-8generic*Not reported
Red Hat/openshift/ose-rhel-coreos-9generic*Not reported

Recommended response

  1. 1Check inventory. Check lockfiles and deployed manifests for Red Hat/openshift/ose-rhel-coreos-8, Red Hat/openshift/ose-rhel-coreos-9.
  2. 2Review the reported fix. Source-reported workaround: 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.

Evidence timeline and material changes

  1. Published upstream

    Aug 3, 2026

    Evidence: source:cvelist:source_dates:source-dates:record

  2. Source modified

    Nov 2, 2026

    Evidence: source:cvelist:source_dates:source-dates:record

  3. First seen by HOL

    Aug 3, 2026

Sources and claim methodology

  • Source referenceaccess.redhat.com
  • Source referenceaccess.redhat.com
  • Source referenceaccess.redhat.com
  • Source referenceaccess.redhat.com
  • Source referenceaccess.redhat.com
  • Source referenceaccess.redhat.com
  • Source referenceaccess.redhat.com
  • Source referencebugzilla.redhat.com
Upstream source description

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.

Quoted source text, attributed separately from HOL analysis.

Related CVEs

  • nvm use --save and nvm install --save write through a symlinked .nvmrc, overwriting any file the user can writeAlso CWE-59