Vulnerability · Published Aug 10, 2026 · Assigned by CERT-PL
CVE-2026-66484Path Traversal in GNU cpio
Medium 4.6
In plain English
A medium-severity path traversal in cpio from GNU. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 9% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
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
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian:12 | cpio | no fix listed | DEBIAN-CVE-2026-66484 |
| Debian:13 | cpio | no fix listed | DEBIAN-CVE-2026-66484 |
| Debian:14 | cpio | no fix listed | DEBIAN-CVE-2026-66484 |
| Ubuntu:22.04:LTS | cpio | 2.13+dfsg-7ubuntu0.2 | UBUNTU-CVE-2026-66484 |
| Ubuntu:22.04:LTS | cpio | 2.13+dfsg-7ubuntu0.2 | USN-8704-1 |
| Ubuntu:24.04:LTS | cpio | 2.15+dfsg-1ubuntu2.1 | USN-8704-1 |
| Ubuntu:24.04:LTS | cpio | 2.15+dfsg-1ubuntu2.1 | UBUNTU-CVE-2026-66484 |
| Ubuntu:26.04:LTS | cpio | 2.15+dfsg-2.1ubuntu0.1 | USN-8704-1 |
| Ubuntu:26.04:LTS | cpio | 2.15+dfsg-2.1ubuntu0.1 | UBUNTU-CVE-2026-66484 |
Affected products (as reported)
Weakness: CWE-22 · Vector: 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
References
- https://cert.pl/en/posts/2026/08/CVE-2026-66484 third-party-advisory
- https://git.savannah.gnu.org/cgit/cpio.git product