CVE-2026-34726 — Copier `_subdirectory` allows template root escape via parent-directory traversal
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…
Published: 2026-04-02 · CVSS: 4.4 · CVSS 3.1
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.
Source: CVE Program · Revision 8b16575c39f1e1810c5e863010da073d2d3285e7