CVE-2025-55201 is a high-severity path traversal vulnerability (CWE-22) affecting versions of the copier-org 'copier' library and CLI application prior to 9.9.1. Copier is a tool used for rendering project templates, commonly employed by developers and organizations to automate project scaffolding. The vulnerability arises because copier exposes certain pathlib.Path objects within the Jinja templating context without properly restricting their input/output methods. This exposure allows a template, even if considered safe, to perform unconstrained filesystem operations such as reading and writing arbitrary files outside the intended directory scope. Essentially, the security model designed to limit filesystem access is bypassed, enabling an attacker to traverse directories and manipulate files arbitrarily. The vulnerability does not require authentication but does require user interaction (e.g., rendering a malicious template). The CVSS 4.0 score is 8.5 (high), reflecting local attack vector, low attack complexity, no privileges required, user interaction needed, and high impact on confidentiality, integrity, and availability. No known exploits are currently in the wild, and the issue is fixed in version 9.9.1 of copier.

For European organizations, this vulnerability poses significant risks, especially for software development teams and CI/CD pipelines that utilize copier for templating and project scaffolding. Exploitation could lead to unauthorized disclosure of sensitive files, modification or deletion of critical configuration or source code files, and potential disruption of development workflows. Since copier is often integrated into automated processes, a successful attack could propagate malicious changes or leak credentials embedded in configuration files. The local attack vector means that attackers would need some level of access to initiate the template rendering process, but given the prevalence of shared development environments and automated build systems, the attack surface is non-trivial. The high impact on confidentiality, integrity, and availability could lead to data breaches, intellectual property theft, and operational downtime. Organizations handling sensitive data or operating in regulated sectors (e.g., finance, healthcare) face compliance risks if this vulnerability is exploited.

European organizations should immediately upgrade all instances of copier to version 9.9.1 or later to remediate this vulnerability. Until upgrades can be applied, restrict copier usage to trusted templates only and avoid rendering templates from unverified or external sources. Implement strict access controls on development and build environments to limit who can execute copier commands. Employ filesystem monitoring to detect unusual read/write operations outside expected directories during template rendering. Integrate static code analysis or template scanning tools to identify unsafe usage of pathlib.Path objects in templates. Additionally, consider sandboxing the copier execution environment to contain potential filesystem access. Regularly audit and review CI/CD pipelines and developer workstations for outdated copier versions and suspicious activity. Finally, raise awareness among developers about the risks of rendering untrusted templates.