Vulnerability · Published Apr 2, 2026 · Assigned by GitHub_M
CVE-2026-34726Copier `_subdirectory` allows template root escape via parent-directory traversal
Medium 4.4
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 0.4% (higher than 34% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
Copier is a library and CLI app for rendering project templates. Prior to version 9.14.1, Copier's _subdirectory setting is documented as the subdirectory to use as the template root. However, the current implementation accepts parent-directory traversal such as .. and uses it directly when selecting the template root. As a result, a template can escape its own directory and make Copier render files from the parent directory without --UNSAFE. This issue has been patched in version 9.14.1.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| PyPI | copier | 9.14.1 | GHSA-85v3-4m8g-hrh6 |
| PyPI | copier | 9.14.1 | PYSEC-2026-2134 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| copier-org | copier | < 9.14.1 |
Weakness: CWE-22 · Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N