copier-org copier up to 9.14.0 _subdirectory path traversal

Summaryinfo

A vulnerability was found in copier-org copier up to 9.14.0. It has been declared as critical. Affected by this issue is the function _subdirectory. Such manipulation leads to path traversal. This vulnerability is traded as CVE-2026-34726. An attack has to be approached locally. There is no exploit available. It is recommended to upgrade the affected component.

Detailsinfo

A vulnerability was found in copier-org copier up to 9.14.0. It has been rated as critical. Affected by this issue is the function _subdirectory. The manipulation with an unknown input leads to a path traversal vulnerability. Using CWE to declare the problem leads to CWE-22. The product uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the product does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory. Impacted is confidentiality, integrity, and availability. CVE summarizes:

Copier is a library and CLI app for rendering project templates. Prior to version 9.14.1, Copier's _subdirectory setting is documented as the subdirectory to use as the template root. However, the current implementation accepts parent-directory traversal such as .. and uses it directly when selecting the template root. As a result, a template can escape its own directory and make Copier render files from the parent directory without --UNSAFE. This issue has been patched in version 9.14.1.

The advisory is shared for download at github.com. This vulnerability is handled as CVE-2026-34726 since 03/30/2026. The exploitation is known to be easy. The attack needs to be approached locally. Successful exploitation requires user interaction by the victim. There are known technical details, but no exploit is available. The MITRE ATT&CK project declares the attack technique as T1006.

Upgrading to version 9.14.1 eliminates this vulnerability. The upgrade is hosted for download at github.com. Applying the patch cb80a3ffc9c3787de3ed837e04ca29a0ff8ca3df is able to eliminate this problem. The bugfix is ready for download at github.com. The best possible mitigation is suggested to be upgrading to the latest version.

Once again VulDB remains the best source for vulnerability data.

Productinfo

Vendor

• copier-org

Name

• copier

Version

• 9.0
• 9.1
• 9.2
• 9.3
• 9.4
• 9.5
• 9.6
• 9.7
• 9.8
• 9.9
• 9.10
• 9.11
• 9.12
• 9.13
• 9.14.0

License

• open-source

Website

• Product: https://github.com/copier-org/copier/

CPE 2.3info

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CPE 2.2info

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