Copier's safe template has filesystem write access outside destination path

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS 4.0

6.9 · CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:N/VI:H/VA:H/SC:N/SI:N/SA:N · score source

EPSS

• CVE-2025-55214: 0.26% estimated exploitation activity in the next 30 days; percentile 18.41 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Impact Copier suggests that it's safe to generate a project from a safe template, i.e. one that doesn't use unsafe features like custom Jinja extensions which would require passing the --UNSAFE,--trust flag. As it turns out, a safe template can currently write files outside the destination path where a project shall be generated or updated. This is possible when rendering a generated directory structure whose rendered path is either a relative parent path or an absolute path. Constructing such paths is possible using Copier's builtin pathjoin Jinja filter and its builtin copierconf.sep variable, which is the platform-native path separator. This way, a malicious template author can create a template that overwrites arbitrary files (according to the user's write permissions), e.g., to cause havoc. Write access via generated relative path Reproducible example: Write access via generated absolute path Reproducible example: - POSIX: - Windows (PowerShell): This scenario is slightly less…

Published by the source

18 Aug 2025, 21:01 UTC

Last modified by the source

7 Jul 2026, 17:57 UTC

Source last checked

26 Oct 2026, 13:32 UTC

1. Revision 3 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-p7q8-grrj-3m8w

2. Revision 2 · amended · 25 Oct 2026

   Reviewed OSV alias/range/CVSS4 correction; package source scopes and original publication preserved. No customer finding resolved.

3. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-p7q8-grrj-3m8w

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# Patch Next advisory brief: CVE-2025-55214

Advisory: Copier's safe template has filesystem write access outside destination path
IDs: CVE-2025-55214, GHSA-p7q8-grrj-3m8w
Record: https://patchnext.com/advisories/cve-2025-55214 (revision 3, source checked 26 Oct 2026, 13:32 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 6.9)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: copier 9.9.1. A vendor fix does not mean a deployment is fixed.

## Affected components
- PyPI copier: affected >= 7.1.0, < 9.9.1; fixed in 9.9.1

## Suggested inspection (read-only)
- `python -m pip show copier`: prints the installed version. Run with the environment that serves production active.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on copier.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-p7q8-grrj-3m8w (OSV record GHSA-p7q8-grrj-3m8w lists affected ranges: PyPI copier >=7.1.0 <9.9.1 (fixed))
- Verified: https://github.com/advisories/GHSA-p7q8-grrj-3m8w (GitHub-reviewed advisory GHSA-p7q8-grrj-3m8w lists affected ranges: PyPI copier >=7.1.0 <9.9.1)

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