Bug 2509845

Summary: CVE-2026-18508 tar: tar: --one-top-level hardlink targets not confined to top-level directory enabling arbitrary file overwrite [fedora-all]
Product: [Fedora] Fedora Reporter: Ganesh <gnaik>
Component: tarAssignee: Pavel Cahyna <pcahyna>
Status: CLOSED ERRATA QA Contact: Fedora Extras Quality Assurance <extras-qa>
Severity: medium Docs Contact:
Priority: medium    
Version: 45CC: kdudka, ovasik, pcahyna, pkubat, praiskup
Target Milestone: ---Keywords: Security, SecurityTracking
Target Release: ---   
Hardware: Unspecified   
OS: Unspecified   
Whiteboard: {"flaws": ["a93a69d7-6cd5-4120-87e5-23932e59b59d"]}
Fixed In Version: tar-1.35-10.fc45 Doc Type: ---
Doc Text:
Story Points: ---
Clone Of: Environment:
Last Closed: 2026-09-12 00:19:12 UTC Type: ---
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Embargoed:
Bug Depends On:    
Bug Blocks: 2509843    

Description Ganesh 2026-07-31 17:24:57 UTC
Disclaimer: Community trackers are created by Red Hat Product Security team on a best effort basis. Package maintainers are required to ascertain if the flaw indeed affects their package, before starting the update process.

A flaw was found in GNU tar. The --one-top-level option is intended to confine extraction under a designated directory, but hardlink targets from the archive are not confined the same way and are resolved relative to the extraction working directory (or the directory given with -C). A crafted archive can create hardlinks inside the --one-top-level directory that point to files outside it. If a suitable symbolic link already exists under the extraction working directory, hardlinking to that symlink can bypass tar's usual symlink-based path protections and allow writing outside the intended top-level directory during a single extraction. Users who rely on --one-top-level as a security boundary when extracting untrusted archives may be affected.

Comment 1 Aoife Moloney 2026-08-17 15:44:35 UTC
This bug appears to have been reported against 'rawhide' during the Fedora Linux 45 development cycle.
Changing version to 45.

Comment 2 Fedora Update System 2026-09-09 14:16:26 UTC
FEDORA-2026-ee1eb89e7b (tar-1.35-10.fc45) has been submitted as an update to Fedora 45.
https://bodhi.fedoraproject.org/updates/FEDORA-2026-ee1eb89e7b

Comment 3 Fedora Update System 2026-09-10 02:17:44 UTC
FEDORA-2026-ee1eb89e7b has been pushed to the Fedora 45 testing repository.
Soon you'll be able to install the update with the following command:
`sudo dnf upgrade --enablerepo=updates-testing --refresh --advisory=FEDORA-2026-ee1eb89e7b`
You can provide feedback for this update here: https://bodhi.fedoraproject.org/updates/FEDORA-2026-ee1eb89e7b

See also https://fedoraproject.org/wiki/QA:Updates_Testing for more information on how to test updates.

Comment 4 Fedora Update System 2026-09-12 00:19:12 UTC
FEDORA-2026-ee1eb89e7b (tar-1.35-10.fc45) has been pushed to the Fedora 45 stable repository.
If problem still persists, please make note of it in this bug report.