copier-org copier up to 9.15.1 Settings copier/_settings.py Path.resolve trust comparison

Summaryinfo

A vulnerability marked as critical has been reported in copier-org copier up to 9.15.1. Affected by this issue is the function Path.resolve of the file copier/_settings.py of the component Settings Handler. Performing a manipulation of the argument trust results in comparison. This vulnerability is known as CVE-2026-53951. Remote exploitation of the attack is possible. No exploit is available.

Detailsinfo

A vulnerability, which was classified as critical, was found in copier-org copier up to 9.15.1. This affects the function Path.resolve of the file copier/_settings.py of the component Settings Handler. The manipulation of the argument trust with an unknown input leads to a comparison vulnerability. CWE is classifying the issue as CWE-697. The product compares two entities in a security-relevant context, but the comparison is incorrect, which may lead to resultant weaknesses. This is going to have an impact on confidentiality, integrity, and availability. The summary by CVE is:

Copier is a library and CLI app for rendering project templates. In versions 9.5.0 through 9.15.1, the `trust` setting's prefix match (`copier/_settings.py`) compares the template URL against a trusted prefix with a raw `str.startswith` and no path normalization, while the URL is normalized when the template is actually fetched (`Path.resolve()` for local paths; libcurl dot-segment removal for `https`). A template reference that textually starts with a trusted prefix but contains `..` is therefore granted trust yet resolves to a different, attacker-controlled template, whose `tasks` / `migrations` / `jinja_extensions` then run without the `--trust` prompt — arbitrary command execution. Version 9.15.2 patches the issue.

The advisory is shared at github.com. This vulnerability is uniquely identified as CVE-2026-53951 since 06/11/2026. The exploitability is told to be easy. It is possible to initiate the attack remotely. No form of authentication is needed for exploitation. It demands that the victim is doing some kind of user interaction. Technical details are known, but no exploit is available.

Upgrading to version 9.15.2 eliminates this vulnerability.

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Productinfo

Vendor

• copier-org

Name

• copier

Version

• 9.15.0
• 9.15.1

Website

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

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CPE 2.2info

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Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

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