Medium severity · published Apr 2, 2026
CVE-2026-34726
Copier `_subdirectory` allows template root escape via parent-directory traversal
4.4
CVSS
0.4%
EPSS
No
On KEV
Description
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.
CVSS vector
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N
Attack vector
Local
Complexity
Low
Privileges
None
User interaction
Required
Confidentiality
Low
Integrity
Low
Availability
None
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.4% · higher than 32% 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-2026-34726
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-34726
Patch
https://github.com/copier-org/copier/commit/cb80a3ffc9c3787de3ed837e04ca29a0ff8ca3df
Release Notes
https://github.com/copier-org/copier/releases/tag/v9.14.1
Exploit
https://github.com/copier-org/copier/security/advisories/GHSA-85v3-4m8g-hrh6
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