CVE-2026-23968: Copier False Vulnerability

MODERATE
Advisory Identifier: GHSA-xjhm-gp88-8pfx
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CVSS 5.5
CWE-61
Published
Advisory Summary

CVE-2026-23968 is a MODERATE (CVSS 5.5) false vulnerability (CWE-61: UNIX Symbolic Link (Symlink) Following) affecting Copier libraries in the PyPI ecosystem. The issue involves false. Remediation is available by upgrading affected packages to version 9.11.2.

CVE-2026-23968 at a Glance

CVE Identifier CVE-2026-23968
GHSA Identifier GHSA-xjhm-gp88-8pfx
Severity MODERATE
CVSS v3.1 Base Score 5.5
CWE Classification CWE-61: UNIX Symbolic Link (Symlink) Following
Affected Product Copier
Package Ecosystem PyPI
Published Date
Last Updated

Security Impact

CVSS: 5.5

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N).

Attack Vector Local (AV:L)
Attack Complexity Low (AC:L)
Privileges Required None (PR:N)
User Interaction Required (UI:R)
Scope Unchanged (S:U)
Confidentiality High (C:H)
Integrity None (I:N)
Availability None (A:N)

How to Fix CVE-2026-23968

To remediate this vulnerability, upgrade all affected Copier dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

copier fixed: 9.11.2 
pip install copier>=9.11.2
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

pip show copier

How to Check if You Are Affected

To determine whether your Python environment is affected by CVE-2026-23968, inspect your installed packages using pip:

pip show copier

Analyze the terminal output to locate any version of Copier in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 9.11.2), your application is affected.

Note: The pip show copier command checks currently installed packages in your active Python environment.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-61: UNIX Symbolic Link (Symlink) Following, where the product, when opening a file or directory, does not sufficiently account for when the file is a symbolic link that resolves to a target outside of the intended control sphere. this could allow an attacker to cause the product to operate on unauthorized files. In Copier, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

### Impact Copier suggests that it's safe to generate a project from a safe template, i.e. one that doesn't use [unsafe](https://copier.readthedocs.io/en/stable/configuring/#unsafe) features like custom Jinja extensions which would require passing the `--UNSAFE,--trust` flag. As it turns out, a safe template can currently include arbitrary files/directories outside the local template clone location by using symlinks along with [`_preserve_symlinks: false`](https://copier.readthedocs.io/en/stable/configuring/#preserve_symlinks) (which is Copier's default setting). Imagine, e.g., a malicious template author who creates a template that reads SSH keys or other secrets from well-known locations and hopes for a user to push the generated project to a public location like [github.com](https://github.com/) where the template author can extract the secrets. Reproducible example: - Illegally include a file in the generated project via symlink resolution: ```shell echo "s3cr3t" > secret.txt mkdir src/ pushd src/ ln -s ../secret.txt stolen-secret.txt popd uvx copier copy src/ dst/ cat dst/stolen-secret.txt #s3cr3t ``` - Illegally include a directory in the generated project via symlink resolution: ```shell mkdir secrets/ pushd secrets/ echo "s3cr3t" > secret.txt popd mkdir src/ pushd src/ ln -s ../secrets stolen-secrets popd uvx copier copy src/ dst/ tree dst/ # dst/ # └── stolen-secrets # └── secret.txt # # 1 directory, 1 file cat dst/stolen-secrets/secret.txt # s3cr3t ``` ### Patches n/a ### Workarounds n/a ### References n/a

CVE-2026-23968 Affected Copier Versions

1 component(s)
Fixed Versions:
9.11.2
Product / Package Ecosystem Affected Versions Fixed Version
copier
pypi/copier
PyPI
< 9.11.2
9.11.2

References

GitHub Advisory / Wiki ADVISORY
https://github.com/copier-org/copier/security/advisories/GHSA-xjhm-gp88-8pfx
NVD — CVE-2026-23968 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-23968
Security Fix Commit FIX COMMIT
https://github.com/copier-org/copier/commit/b3a7b3772d17cf0e7a4481978188c9f536c8d8f6
Copier Source Repository REPOSITORY
https://github.com/copier-org/copier

Frequently Asked Questions

What is CVE-2026-23968?
CVE-2026-23968 is a security vulnerability in Copier involving false under CWE-61: UNIX Symbolic Link (Symlink) Following.
Which Copier versions are affected?
Affected versions include releases prior to 9.11.2 across affected packages: copier.
What version fixes CVE-2026-23968?
Upgrading to 9.11.2 (or the latest patched release for your respective branch) resolves the vulnerability.
Is copier affected?
Yes, copier is affected in releases prior to 9.11.2. Upgrade your dependency to 9.11.2 or later.
What is the CVSS score of CVE-2026-23968?
CVE-2026-23968 has a CVSS v3.1 base score of 5.5 (MODERATE) with vector string CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N.
What CWE is associated with CVE-2026-23968?
CVE-2026-23968 is classified under CWE-61: UNIX Symbolic Link (Symlink) Following (The product, when opening a file or directory, does not sufficiently account for when the file is a symbolic link that resolves to a target outside of the intended control sphere. This could allow an attacker to cause the product to operate on unauthorized files.).
How can I check PyPI dependencies for CVE-2026-23968?
Run the dependency tree command: 'pip show copier'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-xjhm-gp88-8pfx",
  "modified" : "2026-02-02T16:33:40Z",
  "published" : "2026-01-21T22:08:48Z",
  "aliases" : [ "CVE-2026-23968" ],
  "summary" : "Copier safe template has arbitrary filesystem read access via symlinks when _preserve_symlinks: false",
  "details" : "### Impact\n\nCopier suggests that it's safe to generate a project from a safe template, i.e. one that doesn't use [unsafe](https://copier.readthedocs.io/en/stable/configuring/#unsafe) features like custom Jinja extensions which would require passing the `--UNSAFE,--trust` flag. As it turns out, a safe template can currently include arbitrary files/directories outside the local template clone location by using symlinks along with [`_preserve_symlinks: false`](https://copier.readthedocs.io/en/stable/configuring/#preserve_symlinks) (which is Copier's default setting). \n\nImagine, e.g., a malicious template author who creates a template that reads SSH keys or other secrets from well-known locations and hopes for a user to push the generated project to a public location like [github.com](https://github.com/) where the template author can extract the secrets.\n\nReproducible example:\n\n- Illegally include a file in the generated project via symlink resolution:\n\n    ```shell\n    echo \"s3cr3t\" > secret.txt\n\n    mkdir src/\n    pushd src/\n    ln -s ../secret.txt stolen-secret.txt\n    popd\n\n    uvx copier copy src/ dst/\n\n    cat dst/stolen-secret.txt\n    #s3cr3t\n    ```\n\n- Illegally include a directory in the generated project via symlink resolution:\n\n    ```shell\n    mkdir secrets/\n    pushd secrets/\n    echo \"s3cr3t\" > secret.txt\n    popd\n\n    mkdir src/\n    pushd src/\n    ln -s ../secrets stolen-secrets\n    popd\n\n    uvx copier copy src/ dst/\n\n    tree dst/\n    # dst/\n    # └── stolen-secrets\n    #     └── secret.txt\n    #\n    # 1 directory, 1 file\n    cat dst/stolen-secrets/secret.txt\n    # s3cr3t\n    ```\n\n### Patches\n\nn/a\n\n### Workarounds\n\nn/a\n\n### References\n\nn/a",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N"
  }, {
    "type" : "CVSS_V4",
    "score" : "CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "PyPI",
      "name" : "copier"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "9.11.2"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/copier-org/copier/security/advisories/GHSA-xjhm-gp88-8pfx"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-23968"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/copier-org/copier/commit/b3a7b3772d17cf0e7a4481978188c9f536c8d8f6"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/copier-org/copier"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-61" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-01-21T22:08:48Z",
    "nvd_published_at" : "2026-01-21T23:15:52Z"
  }
}