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 root. However, the current implementation accepts parent-directory traversal such as .. and uses it directly when...

CVE-2026-34726

CVE-2026-34726 affects Copier (library/CLI) prior to version 9.14.1. The issue stems from the _subdirectory setting, which is documented as the template root but can accept directory traversal like .., and is used directly to compute the template root. This allows a template to escape its own dir...

Copier `_subdirectory` allows template root escape via parent-directory traversal

Summary 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 ma...

PT-2026-29668

Name of the Vulnerable Software and Affected Versions Copier versions prior to 9.14.1 Description Copier's subdirectory setting, intended to specify the template root, incorrectly allows parent directory traversal sequences like ... This allows a template to escape its directory and render files...