Copier is a library and CLI app for rendering project templates. Prior to version 9.14.1, Copier's _external_data feature allows a template to load YAML files using template-controlled paths. If untrusted templates are in scope, a malicious template can read attacker-chosen YAML-parseable local files that are accessible to the user running Copier and expose their contents in rendered output. This issue has been patched in version 9.14.1.

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.

Copier is a library and CLI app for rendering project templates. Prior to version 9.11.2, Copier suggests that it's safe to generate a project from a safe template, i.e. one that doesn't use unsafe features like custom Jinja extensions which would require passing the `--UNSAFE,--trust` flag. As it turns out, a safe template can currently include arbitrary files/directories outside the local template clone location by using symlinks along with `_preserve_symlinks: false` (which is Copier's default setting). Version 9.11.2 patches the issue.

Copier is a library and CLI app for rendering project templates. Prior to version 9.11.2, Copier suggests that it's safe to generate a project from a safe template, i.e. one that doesn't use unsafe features like custom Jinja extensions which would require passing the `--UNSAFE,--trust` flag. As it turns out, a safe template can currently write to arbitrary directories outside the destination path by using directory a symlink along with `_preserve_symlinks: true` and a generated directory structure whose rendered path is inside the symlinked directory. This way, a malicious template author can create a template that overwrites arbitrary files (according to the user's write permissions), e.g., to cause havoc. Version 9.11.2 patches the issue.