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 that doesn't use unsafe features like custom Jinja extensions which would require passing the --UNSAFE,--trust flag. As it...