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TI-2026-26970 Aliases CVE-2026-34726GHSA-85v3-4m8g-hrh6

Copier `_subdirectory` allows template root escape via parent-directory traversal

Priority MEDIUM 54CWE-22Published · Updated

Key facts

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

Attack profile from CVSS 3.1 · CNA. Fix status from CNA and GitHub.

Summary

Copier is a library and CLI app for rendering project templates. Prior to version 9.14.1, Copier's _subdirectory setting is documented as the subdirectory to use as the template root. However, the current implementation accepts parent-directory traversal such as .. and uses it directly when selecting the template root. As a result, a template can escape its own directory and make Copier render files from the parent directory without --UNSAFE. 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 0.00397 34th 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-85v3-4m8g-hrh6
  • 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-85v3-4m8g-hrh6

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-85v3-4m8g-hrh6 copier (PyPI) Fixed in 9.14.1 Advisory →

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-34726
  2. 2026-10-03 Alias added: GHSA-85v3-4m8g-hrh6

References

Exploit 1

Patch 1

Advisory 1

Other 2

  • TI-2026-26974 Copier `_external_data` allows path traversal and absolute-path local file read without unsafe mode CVSS 3.1MEDIUM 5.5
  • 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