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TI-2026-26974 Aliases CVE-2026-34730GHSA-hgjq-p8cr-gg4h

Copier `_external_data` allows path traversal and absolute-path local file read without unsafe mode

Priority MEDIUM 58CWE-22Published · Updated

Key facts

Attack vector
Local
Privileges required
None
User interaction
Required
Attack complexity
Low
Impact type
Information disclosure
Confidentiality · integrity · availability
High · None · None
Fix status
Fixed

Attack profile from CVSS 3.1 · CNA. Fix status from CNA and GitHub. Impact type from CWE-22 and the CVSS impact.

Summary

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.

Why it matters now

Exploitation Proof of concept CISA SSVC · not in CISA KEV
EPSS 0.00298 22nd percentileScored 2026-11-07
Public exploit Yes 1 exploit referenceTagged by NVD
Fix Fixed copier (copier-org): 9.14.1copier (PyPI): 9.14.1

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
Poc
Automatable
No
Technical impact
Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
copier-orgcopierbefore 9.14.19.14.1Patch availableCNA
—copier (PyPI)before 9.14.19.14.1Patch availableGHSA-hgjq-p8cr-gg4h
  • copier Vendorcopier-org Affected before 9.14.1 Fixed in 9.14.1 Patch available CNA
  • copier (PyPI) Vendor— Affected before 9.14.1 Fixed in 9.14.1 Patch available GHSA-hgjq-p8cr-gg4h

CPE configurations NVD · 1

CPEVersionsRoleVendor
cpe:2.3:a:copier-org:copier:*:*:*:*:*:python:*:*before 9.14.1Vulnerablecopier-org
  • cpe:2.3:a:copier-org:copier:*:*:*:*:*:python:*:* Versions before 9.14.1 Vulnerable ·copier-org

Remediation

  • Fix · CNA copier (copier-org) Fixed in 9.14.1
  • Fix · GHSA-hgjq-p8cr-gg4h copier (PyPI) Fixed in 9.14.1 Advisory →

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-34730
  2. 2026-10-03 Alias added: GHSA-hgjq-p8cr-gg4h

References

Exploit 1

Patch 1

Advisory 1

Other 2

  • TI-2026-26970 Copier `_subdirectory` allows template root escape via parent-directory traversal CVSS 3.1MEDIUM 4.4
  • TI-2026-19328 Copier safe template has arbitrary filesystem write access via directory symlinks when _preserve_symlinks: true CVSS 4.0MEDIUM 6.9
  • TI-2026-19310 Copier safe template has arbitrary filesystem read access via symlinks when _preserve_symlinks: false CVSS 4.0MEDIUM 6.8

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences