CVE-2026-34726 json
Copier `_subdirectory` allows template root escape via parent-directory traversal
published 2026-04-01 7 mo ago modified 2026-07-24 3 mo ago also GHSA-85v3-4m8g-hrh6 , PYSEC-2026-2134 , EUVD-2026-18495
- cvss
- 4.4
- version 3.1, CNA
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 0.4%
- EPSS 0.4% chance of exploitation in 30 days, percentile 34%
- public exploits
- 0
- none known
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.
Patch / fix
- pypi copier 9.14.1
- copier-org copier 9.14.1
CISA SSVC
- Exploitation
- Proof of concept is public
- Automatable
- no
- Technical impact
- partial
- Assessed
- 7 mo ago
Exploit prediction
0.40% chance of exploitation in the next 30 days, higher than 34% of all scored CVEs (FIRST EPSS, 2026-11-08).
Exploits and checks
- github.com https://github.com/copier-org/copier/security/advisories/GHSA-85v3-4m8g-hrh6 referenced PoC, tagged "exploit" by a source, unverified
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| CNA | 3.1 | 4.4 | CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N |
| OSV | 3.1 | 4.4 | CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N |
| GitHub | 3.1 | 4.4 | CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N |
Affected packages
| ecosystem | package | affected | fixed in |
|---|---|---|---|
| pypi | copier | <9.14.1 |
9.14.1 |
Affected products
- copier-org copier
Classification
- Weakness
-
- CWE-22 Improper Limitation of a Pathname to a Restricted Directory
References
-
github.com
/copier-org/copier/commit/cb80a3ffc9c3787de3ed837e04ca29a0ff8ca3df
web, patch
-
github.com
/copier-org/copier/security/advisories/GHSA-85v3-4m8g-hrh6
exploit, web, vendor-advisory, evidence
-
github.com
/copier-org/copier/releases/tag/v9.14.1
web, release-notes, advisory
-
nvd.nist.gov
/vuln/detail/CVE-2026-34726
advisory
-
github.com
/copier-org/copier
package
Sources
- CVE List CVE-2026-34726
- GitHub Advisory GHSA-85v3-4m8g-hrh6
- NVD CVE-2026-34726
- OSV PYSEC-2026-2134
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