---
id: CVE-2026-18508
title: A flaw was found in GNU tar
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 arch…
severity: medium
cvss: 4.4
cvssVector: 'CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N'
cwe:
  - CWE-59
vendor: gnu
product: tar
affected:
  - tar = 1.35
  - openshift_container_platform = 4.0
  - enterprise_linux = 8.0
  - enterprise_linux = 9.0
  - enterprise_linux = 10.0
published: '2026-08-03'
updated: '2026-09-22'
sourceUpdated: '2026-09-22T22:17:11.493'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-18508'
references:
  - url: 'https://access.redhat.com/errata/RHSA-2026:50807'
    label: secalert@redhat.com
  - url: 'https://access.redhat.com/errata/RHSA-2026:61581'
    label: secalert@redhat.com
  - url: 'https://access.redhat.com/errata/RHSA-2026:61586'
    label: secalert@redhat.com
  - url: 'https://access.redhat.com/errata/RHSA-2026:61783'
    label: secalert@redhat.com
  - url: 'https://access.redhat.com/errata/RHSA-2026:66018'
    label: secalert@redhat.com
  - url: 'https://access.redhat.com/errata/RHSA-2026:70390'
    label: secalert@redhat.com
  - url: 'https://access.redhat.com/security/cve/CVE-2026-18508'
    label: secalert@redhat.com
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2509843'
    label: secalert@redhat.com
  - url: >-
      https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-18508.json
  - url: 'https://www.cve.org/CVERecord?id=CVE-2026-18508'
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-18508'
tags:
  - nvd
  - cve.org
  - csaf
  - vex
  - red-hat
epss: 0.00141
epssPercentile: 0.03797
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-08-03T16:02:27.313193Z'
ingestedAt: '2026-09-14T05:37:36.692Z'
patched:
  - enterprise_linux_baseos_v_10
  - enterprise_linux_baseos_v_8
  - enterprise_linux_baseos_v_9
  - discovery 2
  - hardened_images
  - update_infrastructure 5
---

## Overview

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.

## Affected

- `tar = 1.35`
- `openshift_container_platform = 4.0`
- `enterprise_linux = 8.0`
- `enterprise_linux = 9.0`
- `enterprise_linux = 10.0`

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.

## Vendor advisories

- **RHSA-2026:61586** · Red Hat · fixed in: Red Hat Enterprise Linux BaseOS (v. 10) · released 2026-09-01 · [advisory](https://access.redhat.com/errata/RHSA-2026:61586)
- **RHSA-2026:70390** · Red Hat · fixed in: Red Hat Enterprise Linux BaseOS (v. 8) · released 2026-09-22 · [advisory](https://access.redhat.com/errata/RHSA-2026:70390)
- **RHSA-2026:61581** · Red Hat · fixed in: Red Hat Enterprise Linux BaseOS (v. 9) · released 2026-08-31 · [advisory](https://access.redhat.com/errata/RHSA-2026:61581)
- **RHSA-2026:61783** · Red Hat · fixed in: Red Hat Discovery 2 · released 2026-08-31 · [advisory](https://access.redhat.com/errata/RHSA-2026:61783)
- **RHSA-2026:50807** · Red Hat · fixed in: Red Hat Hardened Images · released 2026-08-05 · [advisory](https://access.redhat.com/errata/RHSA-2026:50807)
- **RHSA-2026:66018** · Red Hat · fixed in: Red Hat Update Infrastructure 5 · released 2026-09-09 · [advisory](https://access.redhat.com/errata/RHSA-2026:66018)
- **Red Hat VEX** · Moderate · affected: Red Hat Enterprise Linux 6, Red Hat Enterprise Linux 7, Red Hat OpenShift Container Platform 4 · no fix planned: Red Hat Enterprise Linux 6, Red Hat Enterprise Linux 7, Red Hat OpenShift Container Platform 4 · updated 2026-09-22 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-18508.json)