Vulnerability Description
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.
CVSS Score
HIGH
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| Copier-Org | Copier | < 9.11.2 |
Related Weaknesses (CWE)
References
- https://github.com/copier-org/copier/commit/b3a7b3772d17cf0e7a4481978188c9f536c8Patch
- https://github.com/copier-org/copier/releases/tag/v9.11.2ProductRelease Notes
- https://github.com/copier-org/copier/security/advisories/GHSA-4fqp-r85r-hxqhExploitThird Party Advisory
FAQ
What is CVE-2026-23986?
CVE-2026-23986 is a vulnerability with a CVSS score of 7.1 (HIGH). 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 fe...
How severe is CVE-2026-23986?
CVE-2026-23986 has been rated HIGH with a CVSS base score of 7.1/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2026-23986?
Check the references section above for vendor advisories and patch information. Affected products include: Copier-Org Copier.