{"id":"CVE-2026-23986","aliases":["GHSA-4fqp-r85r-hxqh","PYSEC-2026-1272"],"url":"https://o3.security/vulnerability/CVE-2026-23986","summary":"Copier safe template has arbitrary filesystem write access via directory symlinks when _preserve_symlinks: true","details":"Copier is a library and CLI app for rendering project templates. Prior to version 9.11.2, Copier suggests that it's safe to generate a project from a safe template, i.e. one that doesn't use unsafe features like custom Jinja extensions which would require passing the `--UNSAFE,--trust` flag. As it turns out, a safe template can currently write to arbitrary directories outside the destination path by using directory a symlink along with `_preserve_symlinks: true` and a generated directory structure whose rendered path is inside the symlinked directory. This way, a malicious template author can create a template that overwrites arbitrary files (according to the user's write permissions), e.g., to cause havoc. Version 9.11.2 patches the issue.","published":"2026-01-21T22:20:37.720Z","modified":"2026-08-07T11:49:51.691559803Z","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":"WEB","url":"https://github.com/copier-org/copier/releases/tag/v9.11.2"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/23xxx/CVE-2026-23986.json"},{"type":"ADVISORY","url":"https://github.com/copier-org/copier/security/advisories/GHSA-4fqp-r85r-hxqh"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-23986"},{"type":"FIX","url":"https://github.com/copier-org/copier/commit/b3a7b3772d17cf0e7a4481978188c9f536c8d8f6"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-07T11:49:51.691559803Z"}}