CVE-2026-34726 MEDIUM

CVE-2026-34726: Copier `_subdirectory` allows template root escape via parent-directory traversal

Vendor Copier-Org
Product copier
Weakness CWE-22 · Path traversal
Published April 2, 2026
Last update April 3, 2026

CVSS base score

4.4/10
Attack vector Local
Attack complexity Low
Privileges required None
User interaction Required
Confidentiality Low
Integrity Low

CVSS vector

CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N

What the vulnerability does

01Description

Copier is a library and CLI app for rendering project templates. Prior to version 9.14.1, Copier's _subdirectory setting is documented as the subdirectory to use as the template root. However, the current implementation accepts parent-directory traversal such as .. and uses it directly when selecting the template root. As a result, a template can escape its own directory and make Copier render files from the parent directory without --UNSAFE. This issue has been patched in version 9.14.1.

Key dates

02Disclosure timeline

April 2, 2026 CVE published
April 3, 2026 Record updated