Copier safe template has filesystem write access outside destination path
Key facts
- Attack vector
- Local
- Privileges required
- None
- User interaction
- Passive
- Attack complexity
- Low
- Attack requirements
- None
- Impact type
- —
- Confidentiality · integrity · availability
- None · High · High
- Fix status
- Fixed
Attack profile from CVSS 4.0 · CNA. Fix status from CNA and GitHub.
Summary
Copier library and CLI app for rendering project templates. From 7.1.0 to before 9.9.1, 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 files outside the destination path where a project shall be generated or updated. This is possible when rendering a generated directory structure whose rendered path is either a relative parent path or an absolute path. Constructing such paths is possible using Copier's builtin pathjoin Jinja filter and its builtin _copier_conf.sep variable, which is the platform-native path separator. 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. This vulnerability is fixed in 9.9.1.
Why it matters now
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- Poc
- Automatable
- No
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| copier-org | copier | 7.1.0 to before 9.9.1 | 9.9.1 | Patch available | CNA |
| — | copier (PyPI) | 7.1.0 to before 9.9.1 | 9.9.1 | Patch available | GHSA-p7q8-grrj-3m8w |
- copier Vendorcopier-org Affected 7.1.0 to before 9.9.1 Fixed in 9.9.1 Patch available CNA
- copier (PyPI) Vendor— Affected 7.1.0 to before 9.9.1 Fixed in 9.9.1 Patch available GHSA-p7q8-grrj-3m8w
CPE names Threatist (inferred) · 1
Inferred from how NVD named this product before; not given by a source.
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:a:copier-org:copier:*:*:*:*:*:*:*:* | — | — | copier-org |
- cpe:2.3:a:copier-org:copier:*:*:*:*:*:*:*:* Versions — — ·copier-org
Remediation
- Fix · CNA copier (copier-org) Fixed in 9.9.1
- Fix · GHSA-p7q8-grrj-3m8w copier (PyPI) Fixed in 9.9.1 Advisory →
Timeline
- 2026-10-02 Threatist record created from CVE-2025-55214
- 2026-10-03 Alias added: GHSA-p7q8-grrj-3m8w
References
More copier-org vulnerabilities
- TI-2026-38919 Copier: trust-prefix bypass via path traversal runs tasks unprompted CVSS 4.0HIGH 8.8
- TI-2025-34877 Copier safe template has arbitrary filesystem read/write access CVSS 4.0HIGH 8.5
- TI-2026-45000 Path traversal in copier-org copier CVSS 3.1HIGH 7.5
- TI-2026-26974 Copier `_external_data` allows path traversal and absolute-path local file read without unsafe mode CVSS 3.1MEDIUM 5.5
- TI-2026-26970 Copier `_subdirectory` allows template root escape via parent-directory traversal CVSS 3.1MEDIUM 4.4
- TI-2026-19328 Copier safe template has arbitrary filesystem write access via directory symlinks when _preserve_symlinks: true CVSS 4.0MEDIUM 6.9
Sources
- CVE-2025-55214 · CVE Program
- CVE-2025-55214 · NVD
- FIRST EPSS
- GHSA-p7q8-grrj-3m8w · GitHub Advisory Database · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences