CVE-2026-18508

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

CVE-2026-18508 is fixed in tar on 1 platform, first by RHSA-2026:61586, released July 31, 2026. It is not reported as exploited. Patch Radar priority: Routine.

Routine

CVSS

5.6

Moderate

Exploitation

None reported

No vendor assessment

CISA KEV

Not listed

Not in the Known Exploited Vulnerabilities catalog

EPSS

0.0014

3rd percentile

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.

Where it's fixed

Product	Fixed in	Fix	Released
Linux
tar · RHEL 10	1.35-13.el10_2	RHSA-2026:61586	Jul 31, 2026
tar · RHEL 8	2:1.30-13.el8_10	RHSA-2026:70390	Sep 23, 2026
tar · RHEL 9	2:1.34-13.el9_8	RHSA-2026:61581	Sep 13, 2026
tar · almalinux 10	2:1.35-13.el10_2	ALSA-2026:61586	Aug 31, 2026
tar · almalinux 8	2:1.30-13.el8_10	ALSA-2026:70390	Sep 22, 2026
tar · almalinux 9	2:1.34-13.el9_8	ALSA-2026:61581	Aug 31, 2026
tar · ol 10	2:1.35-13.el10_2	ELSA-2026-61586-0	Sep 1, 2026
tar · ol 8	2:1.30-13.el8_10	ELSA-2026-70390	Sep 23, 2026
tar · ol 9	2:1.34-13.el9_8	ELSA-2026-61581-0	Sep 1, 2026
tar · rocky 10	2:1.35-13.el10_2	RLSA-2026:61586	Sep 11, 2026
tar · rocky 8	2:1.30-13.el8_10	RLSA-2026:70390	Sep 24, 2026
tar · rocky 9	2:1.34-13.el9_8	RLSA-2026:61581	Sep 1, 2026

Details

Published
July 31, 2026
Weakness
Improper Link Resolution Before File Access ('Link Following')
CVSS vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:L
Vendor advisory
https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-18508

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