BaseFortify

Publication date: 2026-01-21

Last updated on: 2026-02-02

Assigner: GitHub, Inc.

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 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.

CVSS Scores

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Meta Information

Published

2026-01-21

Last Modified

2026-02-02

Generated

2026-07-06

AI Q&A

2026-01-22

EPSS Evaluated

2026-07-05

NVD

CVE-2026-23968

Affected Vendors & Products

Vendor	Product	Version / Range
copier-org	copier	to 9.11.2 (exc)

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-61	The product, when opening a file or directory, does not sufficiently account for when the file is a symbolic link that resolves to a target outside of the intended control sphere. This could allow an attacker to cause the product to operate on unauthorized files.

Attack-Flow Graph

Executive Summary

This vulnerability exists in Copier, a library and CLI app for rendering project templates. Before version 9.11.2, Copier incorrectly suggests that generating a project from a safe template is secure. However, a safe template can include arbitrary files or directories outside the local template clone location by exploiting symbolic links combined with the default setting `_preserve_symlinks: false`. This allows unintended file inclusion from outside the template directory. Version 9.11.2 fixes this issue.

Impact Analysis

This vulnerability can lead to the inclusion of arbitrary files or directories from outside the intended template location when generating projects. This could result in unauthorized access to sensitive files or data leakage, potentially compromising the security of your system or project environment.

Mitigation Strategies

Upgrade Copier to version 9.11.2 or later, as this version patches the issue with unsafe symlink handling that allows arbitrary files/directories outside the local template clone location to be included.

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