CVE-2026-34730 — Copier `_external_data` allows path traversal and absolute-path local file read without unsafe mode
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-con…
Published: 2026-04-02 · CVSS: 5.5 · CVSS 3.1
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.
Source: CVE Program · Revision 8b16575c39f1e1810c5e863010da073d2d3285e7