# CVE-2026-66484: Path Traversal in GNU cpio

> Attackers can create hard links to external files during tar extraction, bypassing security restrictions in GNU cpio.

- **Severity:** Medium 4.6 (`CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:A/VC:N/VI:L/VA:N/SC:N/SI:L/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** A user has to click or open something
- **Fix available:** Yes
- **Published:** 10 Aug 2026
- **Updated:** 10 Aug 2026
- **Also known as:** AZL-94695, DEBIAN-CVE-2026-66484, GHSA-rc3p-p5w3-fm9j, RHSA-2026:54508, UBUNTU-CVE-2026-66484

## What is CVE-2026-66484?

CVE-2026-66484 is a medium-severity path traversal vulnerability in GNU cpio, published on 10 Aug 2026. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.

### Official description

GNU cpio contains a Path Traversal vulnerability in its tar archive extraction functionality. When extracting a tar archive in copy-in mode with the --no-absolute-filenames option, the extracted file name is normalized but the tar hard-link target is passed to the link_to_name function without equivalent sanitization before calling link function. A tar archive provided by an attacker, containing a hard-link entry whose linkname is set to an absolute path outside the extraction directory, can cause cpio to create a hard link to an existing file outside the intended extraction directory, breaking the expected guarantee of --no-absolute-filenames and allowing archive-controlled linkage to external files.

This issue has been fixed in commit e2b9cbdd3354d2b1569b7390d1bc15c1930559ad

Weakness: CWE-22 (Improper Limitation of a Pathname to a Restricted Directory)

## Which versions are affected by CVE-2026-66484?


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `cpio` | Red Hat:hummingbird:1 | All versions | 0:2.15-10.1.hum1 |

## How do I fix CVE-2026-66484?

Apply the vendor's patch.

## Is CVE-2026-66484 being exploited?

There is no known exploitation of CVE-2026-66484 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-66484 and fix it if it is affected.

What it is: CVE-2026-66484 is a medium-severity path traversal vulnerability in GNU cpio, published on 10 Aug 2026. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2026-66484 in the wild and no public exploit code.

Affected product: GNU cpio. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-66484/ (Markdown: https://insights.sbomify.com/CVE-2026-66484/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-66484
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-66484
- OSV: https://osv.dev/vulnerability/CVE-2026-66484

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-66484/
Summaries are generated and may contain mistakes; the official description above is the record.