CVE-2026-34730 MEDIUM

CVE-2026-34730: Copier `_external_data` allows path traversal and absolute-path local file read without unsafe mode

Vendor Copier-Org
Product copier
Weakness CWE-22 · Path traversal
Published April 2, 2026
Last update April 3, 2026
View on NVD All CVEs

CVSS base score

5.5/10
Attack vector Local
Attack complexity Low
Privileges required None
User interaction Required
Confidentiality High
Integrity None

CVSS vector

CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N

What the vulnerability does

01Description

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.

Key dates

02Disclosure timeline

April 2, 2026 CVE published
April 3, 2026 Record updated