GNU tar Hardlink Extraction Path Traversal via --one-top-level
CVE-2026-18508 Published on August 3, 2026

Tar: tar: --one-top-level hardlink targets not confined to top-level directory enabling arbitrary file overwrite
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.

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Vulnerability Analysis

CVE-2026-18508 is exploitable with local system access, requires user interaction. This vulnerability is considered to have a low attack complexity. The potential impact of an exploit of this vulnerability is considered to have a small impact on confidentiality and integrity, and no impact on availability.

Attack Vector:
LOCAL
Attack Complexity:
LOW
Privileges Required:
NONE
User Interaction:
REQUIRED
Scope:
UNCHANGED
Confidentiality Impact:
LOW
Integrity Impact:
LOW
Availability Impact:
NONE

Timeline

Reported to Red Hat.

Made public.

Weakness Type

What is an insecure temporary file Vulnerability?

The software attempts to access a file based on the filename, but it does not properly prevent that filename from identifying a link or shortcut that resolves to an unintended resource.

CVE-2026-18508 has been classified to as an insecure temporary file vulnerability or weakness.


Products Associated with CVE-2026-18508

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Red Hat Enterprise Linux (RHEL)
 
Red Hat Hummingbird
 
Red Hat Openshift
 
Red Hat Discovery
 
Red Hat Rhui
 

Affected Versions

Red Hat Enterprise Linux 10: Red Hat Enterprise Linux 9: Red Hat Discovery 2: Red Hat Hardened Images: Red Hat Update Infrastructure 5: Red Hat Update Infrastructure 5: Red Hat Update Infrastructure 5: Red Hat Update Infrastructure 5: Red Hat Update Infrastructure 5: Red Hat Enterprise Linux 6: Red Hat Enterprise Linux 7: Red Hat Enterprise Linux 8: Red Hat Hardened Images: Red Hat Hardened Images: Red Hat Hardened Images: Red Hat Hardened Images: Red Hat Hardened Images: Red Hat Hardened Images: Red Hat Hardened Images: Red Hat Hardened Images: Red Hat Hardened Images: Red Hat Hardened Images: Red Hat OpenShift Container Platform 4: Red Hat OpenShift Container Platform 4: