What’s Vulnerable › Vulnerabilities

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

• Severity: medium (CVSS 5.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.3% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2026-04-02 · updated 2026-07-24
• Weakness: CWE-22

Description

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.

Affected products

• copier-org copier: before 9.14.1 — fixed in 9.14.1

How to fix

Upgrade to a fixed version: copier-org copier 9.14.1. Check the vendor advisory for mitigations.

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

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