CVE-2026-23968 is a vulnerability classified under CWE-61 (Improper Restriction of Symbolic Links) affecting the Copier library and CLI tool used for rendering project templates. Copier versions prior to 9.11.2 have a default configuration where `_preserve_symlinks` is set to false. This setting causes Copier to follow symbolic links within templates, which can be exploited by an attacker to include arbitrary files or directories outside the local template clone location. The vulnerability arises because Copier assumes that templates without unsafe features (like custom Jinja extensions) are safe, but symlinks can bypass this assumption. An attacker can craft a template that includes symlinks pointing to sensitive files or directories on the host system. When a user generates a project from such a template, Copier will follow these symlinks and include the linked content, potentially exposing sensitive data or overwriting files. Exploitation requires user interaction to run Copier with the malicious template but does not require elevated privileges or authentication. The vulnerability has a CVSS 4.0 score of 6.8, reflecting a medium severity impact primarily on confidentiality due to unauthorized file inclusion. The issue is resolved in Copier version 9.11.2 by changing the handling of symlinks to prevent following them by default or by other protective measures.

For European organizations, this vulnerability poses a risk of unauthorized disclosure or modification of files during automated project templating processes. Organizations relying on Copier for software development, DevOps automation, or infrastructure as code could inadvertently expose sensitive configuration files, credentials, or proprietary code if malicious or compromised templates are used. This could lead to data breaches, intellectual property loss, or disruption of development workflows. The impact is particularly significant for sectors with strict data protection requirements such as finance, healthcare, and government. Additionally, organizations using shared or third-party templates from untrusted sources are at higher risk. The vulnerability does not directly enable remote code execution but can facilitate further attacks if sensitive files are exposed. Given the medium severity and ease of exploitation through user interaction, the threat is non-trivial but manageable with proper controls.

European organizations should immediately upgrade Copier to version 9.11.2 or later to apply the patch that addresses this vulnerability. Until upgraded, users should avoid generating projects from untrusted or unknown templates, especially those that could contain symlinks. It is recommended to audit existing templates for symlink usage and enforce policies to restrict template sources to trusted repositories. Additionally, organizations can configure Copier to preserve symlinks (`_preserve_symlinks: true`) if this aligns with their security posture, preventing automatic following of symlinks. Implementing file system monitoring and access controls to detect or block unauthorized file access during template generation can further reduce risk. Educating developers and DevOps teams about the risks of using unverified templates and enforcing code review processes for templates can help prevent exploitation. Finally, integrating template scanning tools that detect unsafe symlink usage before deployment is advisable.