CVE-2026-18508
MEDIUM 4.4A 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.
No known exploitation, public exploit, or elevated probability at this time. Track for changes.
Exploitation likelihood
0.1%chance of exploitation in 30 days · 3rd percentile
Impact if exploited
4.4CVSS 3.1 · MEDIUM
- ConfidentialityLow
- IntegrityLow
- AvailabilityNone
What an attacker needs
- ⚠Access: Requires local access to the host
- ✓Privileges: No account or privileges required
- ⚠User interaction: A user must take an action (click / open a file)
- ✓Complexity: No special conditions — reliably repeatable
✓ lowers the bar for an attacker · ⚠ raises it
Proof of concept & exploit code
- github-search Search GitHub for public PoC repos
Test against your own equipment
curl -s https://vulnpedia.com/cve/CVE-2026-18508/poc.jsonMachine-readable PoC index for this CVE (for automation).Listed for defensive triage, patch verification, and authorized testing on systems you own. Machine-readable: /cve/CVE-2026-18508/poc.json
Affected
Products Red Hat Hardened Images Red Hat Enterprise Linux 10 Red Hat Enterprise Linux 6 Red Hat Enterprise Linux 7 Red Hat Enterprise Linux 8 Red Hat Enterprise Linux 9 Red Hat Openshift Container Platform 4 Tar Openshift Container Platform Enterprise Linux
Weakness (CWE)
- CWE-59: Improper Link Resolution Before File Access ('Link Following')
CVSS vector
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N
Known Affected Software Configurations
| Vendor | Product | Version range |
|---|---|---|
| Gnu | Tar | 1.35 |
| Redhat | Openshift Container Platform | 4.0 |
| Redhat | Enterprise Linux | 8.0 |
| Redhat | Enterprise Linux | 9.0 |
| Redhat | Enterprise Linux | 10.0 |
All CVSS metrics
- MEDIUM 4.4 v3.1 · CNA Primary
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N - MEDIUM 4.4 v3.1 · NVD Secondary
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N