CVE-2025-55214: Copier-Org Copier

Medium severity, CVSS 6.9. EPSS: 0.3% chance of exploitation in the next 30 days.

Copier library and CLI app for rendering project templates. From 7.1.0 to before 9.9.1, 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 files outside the destination path where a project shall be generated or updated. This is possible when rendering a generated directory structure whose rendered path is either a relative parent path or an absolute path. Constructing such paths is possible using Copier's builtin pathjoin Jinja filter and its builtin _copier_conf.sep variable, which is the platform-native path separator. 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. This vulnerability is fixed in 9.9.1.

Affected products

• Copier-Org Copier: from 7.1.0, before 9.9.1 (fixed in 9.9.1)

Published 2025-08-18. Last modified 2026-06-17.