CVE-2026-34730

EUVD-2026-18497

02.04.2026, 19:21

Copier is a library and CLI app for rendering project templates. Prior to version 9.14.1, Copier's _external_data feature allows a template to load YAML files using template-controlled paths. If untrusted templates are in scope, a malicious template can read attacker-chosen YAML-parseable local files that are accessible to the user running Copier and expose their contents in rendered output. This issue has been patched in version 9.14.1.

Path Traversal

Provider	Type	Base Score	Atk. Vector	Atk. Complexity	Priv. Required	Vector
NIST	Primary	5.5 MEDIUM	LOCAL	LOW	NONE	CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N
GitHub_M	CNA	5.5 MEDIUM	LOCAL	LOW	NONE	CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N

Base Score

CVSS 3.x

EPSS Score

Percentile: Unknown

Affected Products (NVD)

Vendor	Product	Version
copier-org	copier	𝑥 < 9.14.1

𝑥

= Vulnerable software versions

Common Weakness Enumeration

CWE-22 - Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')
The software uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the software does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory.

References

https://github.com/copier-org/copier/commit/5413062eb17b73dc885f5e645cdc161e69ef641b

https://github.com/copier-org/copier/releases/tag/v9.14.1

https://github.com/copier-org/copier/security/advisories/GHSA-hgjq-p8cr-gg4h