CVE-2026-23986 — Copier safe template has arbitrary filesystem write access via directory symlinks when _preserve_symlinks: true
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 tha…
Published: 2026-01-21 · CVSS: 6.9 · CVSS 4.0
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.
Source: CVE Program · Revision 8b16575c39f1e1810c5e863010da073d2d3285e7