Medium severity · published Apr 2, 2026
CVE-2026-34730
Copier `_external_data` allows path traversal and absolute-path local file read without unsafe mode
5.5
CVSS
0.3%
EPSS
No
On KEV
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.
CVSS vector
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N
Attack vector
Local
Complexity
Low
Privileges
None
User interaction
Required
Confidentiality
High
Integrity
None
Availability
None
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.3% · higher than 21% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
CO
copier · copier-org
< 9.14.1 · source: vendor, NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-34730
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-34730
Patch
https://github.com/copier-org/copier/commit/5413062eb17b73dc885f5e645cdc161e69ef641b
Release Notes
https://github.com/copier-org/copier/releases/tag/v9.14.1
Exploit
https://github.com/copier-org/copier/security/advisories/GHSA-hgjq-p8cr-gg4h
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