Vulnerability · Published Aug 18, 2025 · Assigned by GitHub_M
CVE-2025-55214Copier safe template has filesystem write access outside destination path
Medium 6.9
In plain English
A medium-severity path traversal in copier from copier-org. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 18% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
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.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| PyPI | copier | 9.9.1 | GHSA-p7q8-grrj-3m8w |
| PyPI | copier | 9.9.1 | PYSEC-2026-1273 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| copier-org | copier | >= 7.1.0, < 9.9.1 |
Weakness: CWE-22 · Vector: CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:N/VI:H/VA:H/SC:N/SI:N/SA:N