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

CVE-2026-66484 is fixed in 2 products on 1 platform, first by cpio 2.15+dfsg-2.1ubuntu0.1, released August 10, 2026. It is not reported as exploited. Patch Radar priority: Routine.

- Web page: https://patchblox.com/security/cve/CVE-2026-66484
- Priority: Routine
- CVSS: n/a (Moderate)
- EPSS: 0.0020
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Aug 10, 2026
- Weakness: Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')
- Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-66484

## 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

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | cpio Ubuntu 18.04.6 LTS (bionic) | 2.12+dfsg-6ubuntu0.18.04.4+esm1 | [cpio 2.12+dfsg-6ubuntu0.18.04.4+esm1](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-cpio-2.12-dfsg-6ubuntu0.18.04.4-esm1.md) | Sep 3, 2026 |
| Linux | cpio Ubuntu 20.04 LTS (focal) | 2.13+dfsg-2ubuntu0.4+esm1 | [cpio 2.13+dfsg-2ubuntu0.4+esm1](https://patchblox.com/security/data/fix/linux/ubuntu-focal-cpio-2.13-dfsg-2ubuntu0.4-esm1.md) | Sep 3, 2026 |
| Linux | cpio Ubuntu 22.04.1 LTS (jammy) | 2.13+dfsg-7ubuntu0.2 | [cpio 2.13+dfsg-7ubuntu0.2](https://patchblox.com/security/data/fix/linux/ubuntu-jammy-cpio-2.13-dfsg-7ubuntu0.2.md) | Sep 3, 2026 |
| Linux | cpio Ubuntu 24.04.5 LTS (noble) | 2.15+dfsg-1ubuntu2.1 | [cpio 2.15+dfsg-1ubuntu2.1](https://patchblox.com/security/data/fix/linux/ubuntu-noble-cpio-2.15-dfsg-1ubuntu2.1.md) | Sep 3, 2026 |
| Linux | cpio Ubuntu 26.04.1 LTS (resolute) | 2.15+dfsg-2.1ubuntu0.1 | [cpio 2.15+dfsg-2.1ubuntu0.1](https://patchblox.com/security/data/fix/linux/ubuntu-resolute-cpio-2.15-dfsg-2.1ubuntu0.1.md) | Aug 10, 2026 |
| Linux | cpio opensuse-leap 16.0 | 2.15-160000.3.1 | [OPENSUSE-SU-2026:21747-1](https://patchblox.com/security/data/fix/linux/opensuse-su-2026-21747-1.md) | Sep 3, 2026 |
| Linux | cpio sles 15.7 | 2.13-150400.3.10.1 | [SUSE-SU-2026:4012-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-4012-1.md) | Sep 7, 2026 |
| Linux | cpio sles 16.0 | 2.15-160000.3.1 | [SUSE-SU-2026:23612-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-23612-1.md) | Sep 3, 2026 |
| Linux | cpio-win32 Ubuntu 18.04.6 LTS (bionic) | 2.12+dfsg-6ubuntu0.18.04.4+esm1 | [cpio-win32 2.12+dfsg-6ubuntu0.18.04.4+esm1](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-cpio-win32-2.12-dfsg-6ubuntu0.18.04.4-esm1.md) | Sep 3, 2026 |
| Linux | cpio-win32 Ubuntu 20.04 LTS (focal) | 2.13+dfsg-2ubuntu0.4+esm1 | [cpio-win32 2.13+dfsg-2ubuntu0.4+esm1](https://patchblox.com/security/data/fix/linux/ubuntu-focal-cpio-win32-2.13-dfsg-2ubuntu0.4-esm1.md) | Sep 3, 2026 |
| Linux | cpio-win32 Ubuntu 22.04.1 LTS (jammy) | 2.13+dfsg-7ubuntu0.2 | [cpio-win32 2.13+dfsg-7ubuntu0.2](https://patchblox.com/security/data/fix/linux/ubuntu-jammy-cpio-win32-2.13-dfsg-7ubuntu0.2.md) | Sep 3, 2026 |

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