CVE-2026-18508
Tar: tar: --one-top-level hardlink targets not confined to top-level directory enabling arbitrary file overwrite
No known exploitation. EPSS puts it in the 3rd percentile. A vendor fix is available.
What to do
The vendor has published a fix. Version details are below where the sources state them.
What it is
From the CVE record
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.
In plain language
No plain-language summary for this CVE yet.
Exploitation
Where each signal puts this CVE on the scale from published to confirmed exploited.
- CISA KEV
Not in the catalog. CISA has not confirmed exploitation.
- Public exploits
No public exploit or proof of concept found in the sources we track.
- EPSS
0.1% chance of exploitation activity in the next 30 days, which ranks it in the 3rd percentile of scored CVEs.
Exploit Prediction Scoring System, FIRST.org. A probability, not a confirmation.
Lifecycle
33 events over 50 days, from the signal feeds we watch.
- Patch availableworkaround available, record updated
- Patch availableworkaround available, record updated
- OpenVAS check added
- Patch availablepatch available, workaround available, workaround available, record updated, record updated
- Patch availablepatch available, workaround available, workaround available, record updated, record updated
- Patch availableworkaround available, record updated
Affected products
- Red Hat Enterprise Linux 10Operating Systems / linux-distro
- Red Hat Discovery 2Enterprise Software / itsm-monitoring
- Red Hat Hardened ImagesOperating Systems / linux-distro
- Red Hat Update Infrastructure 5Operating Systems / linux-distro
- Red Hat OpenShift Container Platform 4Cloud & SaaS / container-orchestration
- openshift container platformOperating Systems / linux-distro
And 5 more affected products. See all after sign-in
Technical detail
CVSS 3.1 vector
Open in the CVSS calculatorCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N
Scored 4.4 by NVD.
How it is reached
- Attack Vector LocalRequires local access to the vulnerable system (e.g. local login, malicious file)
- Attack Complexity LowNo special conditions — the attack can be reliably reproduced
- Privileges Required NoneNo authentication required — anyone can exploit this
- User Interaction RequiredA user must click a link, open a file, or perform some action
Scope
- Scope UnchangedImpact is limited to the vulnerable component itself
Impact if exploited
- Confidentiality LowSome restricted information is disclosed, but limited in scope
- Integrity LowData modification is possible but limited in scope or consequence
- Availability NoneNo availability impact
Weaknesses
ATT&CK techniques
Mapped from the weaknesses above (CWE to ATT&CK), not observed in attacks.
Sources
References in the record
- access.redhat.com/errata/RHSA-2026:50807
- access.redhat.com/errata/RHSA-2026:61581
- access.redhat.com/errata/RHSA-2026:61586
And 5 more references. See all after sign-in
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