Vulnerability-Lookup

PYSEC-2026-1273

Vulnerability from pysec - Published: 2026-07-07 16:03 - Updated: 2026-07-07 17:23

Details

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 _copier_conf.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:

echo "foo" > forbidden.txt
mkdir src/
echo "bar" > "src/{{ pathjoin('..', 'forbidden.txt') }}"
uvx copier copy src/ dst/
cat forbidden.txt

Write access via generated absolute path

Reproducible example:

POSIX:

```shell

Assumption: The current working directory is /tmp/test-copier-vulnerability/

echo "foo" > forbidden.txt mkdir src/ echo "bar" > "src/{{ pathjoin(_copier_conf.sep, 'tmp', 'test-copier-vulnerability', 'forbidden.txt') }}" uvx --from copier python -O -m copier copy --overwrite src/ dst/ cat forbidden.txt ```
Windows (PowerShell):

```powershell

Assumption: The current working directory is C:\Users\<user>\Temp\test-copier-vulnerability

echo "foo" > forbidden.txt mkdir src Set-Content -Path src\copier.yml @' drive: type: str default: "C:" when: false '@ echo "bar" > "src{{ pathjoin(drive, 'Users', '', 'Temp', 'test-copier-vulnerability', 'forbidden.txt') }}" uvx --from copier python -O -m copier copy --overwrite src dst cat forbidden.txt ```

This scenario is slightly less severe, as Copier has a few assertions of the destination path being relative which would typically be raised. But python -O (or PYTHONOPTIMIZE=x) removes asserts, so these guards may be ineffective. In addition, this scenario will prompt for overwrite confirmation or require the --overwrite flag for non-interactive mode; yet malicious file writes might go unnoticed.

Severity

6.9 (Medium)


                  
                    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

Impacted products

Name	purl
copier	pkg:pypi/copier

Aliases

JSON

To clipboard

{
  "affected": [
    {
      "package": {
        "ecosystem": "PyPI",
        "name": "copier",
        "purl": "pkg:pypi/copier"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "7.1.0"
            },
            {
              "fixed": "9.9.1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "7.1.0",
        "7.2.0",
        "8.0.0",
        "8.1.0",
        "8.2.0",
        "8.3.0",
        "9.0.1",
        "9.1.0",
        "9.1.1",
        "9.2.0",
        "9.3.0",
        "9.3.1",
        "9.4.0",
        "9.4.1",
        "9.5.0",
        "9.6.0",
        "9.7.0",
        "9.7.1",
        "9.8.0",
        "9.9.0"
      ]
    }
  ],
  "aliases": [
    "CVE-2025-55214",
    "GHSA-p7q8-grrj-3m8w"
  ],
  "details": "### Impact\n\nCopier suggests that it\u0027s safe to generate a project from a safe template, i.e. one that doesn\u0027t 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 write files outside the destination path where a project shall be generated or updated. This is possible when rendering a [generated directory structure](https://copier.readthedocs.io/en/stable/configuring/#generating-a-directory-structure) whose rendered path is either a relative parent path or an absolute path. Constructing such paths is possible using Copier\u0027s builtin `pathjoin` Jinja filter and its builtin `_copier_conf.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\u0027s write permissions), e.g., to cause havoc.\n\n#### Write access via generated relative path\n\nReproducible example:\n\n```shell\necho \"foo\" \u003e forbidden.txt\nmkdir src/\necho \"bar\" \u003e \"src/{{ pathjoin(\u0027..\u0027, \u0027forbidden.txt\u0027) }}\"\nuvx copier copy src/ dst/\ncat forbidden.txt\n```\n\n#### Write access via generated absolute path\n\nReproducible example:\n\n- POSIX:\n\n    ```shell\n    # Assumption: The current working directory is `/tmp/test-copier-vulnerability/`\n    echo \"foo\" \u003e forbidden.txt\n    mkdir src/\n    echo \"bar\" \u003e \"src/{{ pathjoin(_copier_conf.sep, \u0027tmp\u0027, \u0027test-copier-vulnerability\u0027, \u0027forbidden.txt\u0027) }}\"\n    uvx --from copier python -O -m copier copy --overwrite src/ dst/\n    cat forbidden.txt\n    ```\n\n- Windows (PowerShell):\n\n    ```powershell\n    # Assumption: The current working directory is `C:\\Users\\\u003cuser\u003e\\Temp\\test-copier-vulnerability`\n    echo \"foo\" \u003e forbidden.txt\n    mkdir src\n    Set-Content -Path src\\copier.yml @\u0027\n    drive:\n      type: str\n      default: \"C:\"\n      when: false\n    \u0027@\n    echo \"bar\" \u003e \"src\\{{ pathjoin(drive, \u0027Users\u0027, \u0027\u003cuser\u003e\u0027, \u0027Temp\u0027, \u0027test-copier-vulnerability\u0027, \u0027forbidden.txt\u0027) }}\"\n    uvx --from copier python -O -m copier copy --overwrite src dst\n    cat forbidden.txt\n    ```\n\nThis scenario is slightly less severe, as Copier has a few [assertions of the destination path being relative](https://github.com/copier-org/copier/blob/d106ea543fd26e1ac1b9a3dcef3e99cc70fdf57c/copier/_main.py#L747) which would typically be raised. But `python -O` (or `PYTHONOPTIMIZE=x`) removes asserts, so these guards may be ineffective. In addition, this scenario will prompt for overwrite confirmation or require the `--overwrite` flag for non-interactive mode; yet malicious file writes might go unnoticed.",
  "id": "PYSEC-2026-1273",
  "modified": "2026-07-07T17:23:57.495026Z",
  "published": "2026-07-07T16:03:01.489150Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/copier-org/copier/security/advisories/GHSA-p7q8-grrj-3m8w"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2025-55214"
    },
    {
      "type": "WEB",
      "url": "https://github.com/copier-org/copier/commit/fdbc0167cc22780b497e4db176feaf6f024757d6"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/copier-org/copier"
    },
    {
      "type": "PACKAGE",
      "url": "https://pypi.org/project/copier"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/advisories/GHSA-p7q8-grrj-3m8w"
    }
  ],
  "severity": [
    {
      "score": "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",
      "type": "CVSS_V4"
    }
  ],
  "summary": "Copier\u0027s safe template has filesystem write access outside destination path"
}

BREW-COPIER-CVE-2025-55214 (GHSA-P7Q8-GRRJ-3M8W)

Vulnerability from osv_homebrew – Published: 2026-08-13 16:41 – Updated: 2026-09-17 19:13 – Source website

Summary

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

Details

Impact

Write access via generated relative path

Reproducible example:

echo "foo" > forbidden.txt
mkdir src/
echo "bar" > "src/{{ pathjoin('..', 'forbidden.txt') }}"
uvx copier copy src/ dst/
cat forbidden.txt

Write access via generated absolute path

Reproducible example:

POSIX:

```shell

Assumption: The current working directory is /tmp/test-copier-vulnerability/

echo "foo" > forbidden.txt mkdir src/ echo "bar" > "src/{{ pathjoin(_copier_conf.sep, 'tmp', 'test-copier-vulnerability', 'forbidden.txt') }}" uvx --from copier python -O -m copier copy --overwrite src/ dst/ cat forbidden.txt ```
Windows (PowerShell):

```powershell

Assumption: The current working directory is C:\Users\<user>\Temp\test-copier-vulnerability

echo "foo" > forbidden.txt mkdir src Set-Content -Path src\copier.yml @' drive: type: str default: "C:" when: false '@ echo "bar" > "src{{ pathjoin(drive, 'Users', '', 'Temp', 'test-copier-vulnerability', 'forbidden.txt') }}" uvx --from copier python -O -m copier copy --overwrite src dst cat forbidden.txt ```

Severity

6.9 (Medium)


                    
                      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

References

URL

Type

	https://github.com/copier-org/copier/security/adv…	WEB
	https://nvd.nist.gov/vuln/detail/CVE-2025-55214	ADVISORY
	https://github.com/copier-org/copier/commit/fdbc0…	WEB
	https://github.com/copier-org/copier	PACKAGE

JSON

To clipboard

{
  "affected": [
    {
      "ecosystem_specific": {
        "fix": "bump",
        "range_state": "fixed",
        "upstream_fixed_in": "9.9.1"
      },
      "package": {
        "ecosystem": "Homebrew",
        "name": "copier",
        "purl": "pkg:brew/copier"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "7.1.0"
            },
            {
              "fixed": "9.9.1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "database_specific": {
    "confidence": "high",
    "source": "matched",
    "strategy": "registry",
    "upstream_evidence": [
      {
        "ecosystem": "PyPI",
        "key": "pkg:pypi/copier@9.18.2",
        "name": "copier",
        "strategy": "registry",
        "subject_version": "9.18.2"
      }
    ]
  },
  "details": "### Impact\n\nCopier suggests that it\u0027s safe to generate a project from a safe template, i.e. one that doesn\u0027t 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 write files outside the destination path where a project shall be generated or updated. This is possible when rendering a [generated directory structure](https://copier.readthedocs.io/en/stable/configuring/#generating-a-directory-structure) whose rendered path is either a relative parent path or an absolute path. Constructing such paths is possible using Copier\u0027s builtin `pathjoin` Jinja filter and its builtin `_copier_conf.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\u0027s write permissions), e.g., to cause havoc.\n\n#### Write access via generated relative path\n\nReproducible example:\n\n```shell\necho \"foo\" \u003e forbidden.txt\nmkdir src/\necho \"bar\" \u003e \"src/{{ pathjoin(\u0027..\u0027, \u0027forbidden.txt\u0027) }}\"\nuvx copier copy src/ dst/\ncat forbidden.txt\n```\n\n#### Write access via generated absolute path\n\nReproducible example:\n\n- POSIX:\n\n    ```shell\n    # Assumption: The current working directory is `/tmp/test-copier-vulnerability/`\n    echo \"foo\" \u003e forbidden.txt\n    mkdir src/\n    echo \"bar\" \u003e \"src/{{ pathjoin(_copier_conf.sep, \u0027tmp\u0027, \u0027test-copier-vulnerability\u0027, \u0027forbidden.txt\u0027) }}\"\n    uvx --from copier python -O -m copier copy --overwrite src/ dst/\n    cat forbidden.txt\n    ```\n\n- Windows (PowerShell):\n\n    ```powershell\n    # Assumption: The current working directory is `C:\\Users\\\u003cuser\u003e\\Temp\\test-copier-vulnerability`\n    echo \"foo\" \u003e forbidden.txt\n    mkdir src\n    Set-Content -Path src\\copier.yml @\u0027\n    drive:\n      type: str\n      default: \"C:\"\n      when: false\n    \u0027@\n    echo \"bar\" \u003e \"src\\{{ pathjoin(drive, \u0027Users\u0027, \u0027\u003cuser\u003e\u0027, \u0027Temp\u0027, \u0027test-copier-vulnerability\u0027, \u0027forbidden.txt\u0027) }}\"\n    uvx --from copier python -O -m copier copy --overwrite src dst\n    cat forbidden.txt\n    ```\n\nThis scenario is slightly less severe, as Copier has a few [assertions of the destination path being relative](https://github.com/copier-org/copier/blob/d106ea543fd26e1ac1b9a3dcef3e99cc70fdf57c/copier/_main.py#L747) which would typically be raised. But `python -O` (or `PYTHONOPTIMIZE=x`) removes asserts, so these guards may be ineffective. In addition, this scenario will prompt for overwrite confirmation or require the `--overwrite` flag for non-interactive mode; yet malicious file writes might go unnoticed.",
  "id": "BREW-copier-CVE-2025-55214",
  "modified": "2026-09-17T19:13:35Z",
  "published": "2026-08-13T16:41:06Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/copier-org/copier/security/advisories/GHSA-p7q8-grrj-3m8w"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2025-55214"
    },
    {
      "type": "WEB",
      "url": "https://github.com/copier-org/copier/commit/fdbc0167cc22780b497e4db176feaf6f024757d6"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/copier-org/copier"
    }
  ],
  "schema_version": "1.7.3",
  "severity": [
    {
      "score": "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",
      "type": "CVSS_V4"
    }
  ],
  "summary": "Copier\u0027s safe template has filesystem write access outside destination path",
  "upstream": [
    "GHSA-p7q8-grrj-3m8w",
    "CVE-2025-55214",
    "PYSEC-2026-1273"
  ]
}

CVE-2025-55214 (GCVE-0-2025-55214)

Vulnerability from cvelistv5 – Published: 2025-08-18 16:36 – Updated: 2025-08-18 19:47

Title

Copier safe template has filesystem write access outside destination path

Summary

Copier library and CLI app for rendering project templates. From 7.1.0 to before 9.9.1, 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 _copier_conf.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. This vulnerability is fixed in 9.9.1.

Severity

6.9 (Medium)


                        
                          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

SSVC

Exploitation: poc Automatable: no Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2025-08-18 19:46 UTC

CWE

CWE-22 - Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')

Assigner

GitHub_M mitre root

References

2 references

URL	Tags
https://github.com/copier-org/copier/security/adv…	x_refsource_CONFIRM
https://github.com/copier-org/copier/commit/fdbc0…	x_refsource_MISC

Impacted products

1 product

Vendor	Product	Version
copier-org	copier	Affected: >= 7.1.0, < 9.9.1

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2025-55214",
                "options": [
                  {
                    "Exploitation": "poc"
                  },
                  {
                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2025-08-18T19:46:44.392978Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2025-08-18T19:47:31.803Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "product": "copier",
          "vendor": "copier-org",
          "versions": [
            {
              "status": "affected",
              "version": "\u003e= 7.1.0, \u003c 9.9.1"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "Copier library and CLI app for rendering project templates. From 7.1.0 to before 9.9.1, Copier suggests that it\u0027s safe to generate a project from a safe template, i.e. one that doesn\u0027t 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\u0027s builtin pathjoin Jinja filter and its builtin _copier_conf.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\u0027s write permissions), e.g., to cause havoc. This vulnerability is fixed in 9.9.1."
        }
      ],
      "metrics": [
        {
          "cvssV4_0": {
            "attackComplexity": "LOW",
            "attackRequirements": "NONE",
            "attackVector": "LOCAL",
            "baseScore": 6.9,
            "baseSeverity": "MEDIUM",
            "privilegesRequired": "NONE",
            "subAvailabilityImpact": "NONE",
            "subConfidentialityImpact": "NONE",
            "subIntegrityImpact": "NONE",
            "userInteraction": "PASSIVE",
            "vectorString": "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",
            "version": "4.0",
            "vulnAvailabilityImpact": "HIGH",
            "vulnConfidentialityImpact": "NONE",
            "vulnIntegrityImpact": "HIGH"
          }
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-22",
              "description": "CWE-22: Improper Limitation of a Pathname to a Restricted Directory (\u0027Path Traversal\u0027)",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2025-08-18T16:36:46.621Z",
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "shortName": "GitHub_M"
      },
      "references": [
        {
          "name": "https://github.com/copier-org/copier/security/advisories/GHSA-p7q8-grrj-3m8w",
          "tags": [
            "x_refsource_CONFIRM"
          ],
          "url": "https://github.com/copier-org/copier/security/advisories/GHSA-p7q8-grrj-3m8w"
        },
        {
          "name": "https://github.com/copier-org/copier/commit/fdbc0167cc22780b497e4db176feaf6f024757d6",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/copier-org/copier/commit/fdbc0167cc22780b497e4db176feaf6f024757d6"
        }
      ],
      "source": {
        "advisory": "GHSA-p7q8-grrj-3m8w",
        "discovery": "UNKNOWN"
      },
      "title": "Copier safe template has filesystem write access outside destination path"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
    "assignerShortName": "GitHub_M",
    "cveId": "CVE-2025-55214",
    "datePublished": "2025-08-18T16:36:46.621Z",
    "dateReserved": "2025-08-08T21:55:07.967Z",
    "dateUpdated": "2025-08-18T19:47:31.803Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.1"
}

GHSA-P7Q8-GRRJ-3M8W

Vulnerability from github – Published: 2025-08-18 21:01 – Updated: 2025-08-18 21:01

Summary

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

Details

Impact

Write access via generated relative path

Reproducible example:

echo "foo" > forbidden.txt
mkdir src/
echo "bar" > "src/{{ pathjoin('..', 'forbidden.txt') }}"
uvx copier copy src/ dst/
cat forbidden.txt

Write access via generated absolute path

Reproducible example:

POSIX:

```shell

Assumption: The current working directory is /tmp/test-copier-vulnerability/

echo "foo" > forbidden.txt mkdir src/ echo "bar" > "src/{{ pathjoin(_copier_conf.sep, 'tmp', 'test-copier-vulnerability', 'forbidden.txt') }}" uvx --from copier python -O -m copier copy --overwrite src/ dst/ cat forbidden.txt ```
Windows (PowerShell):

```powershell

Assumption: The current working directory is C:\Users\<user>\Temp\test-copier-vulnerability

echo "foo" > forbidden.txt mkdir src Set-Content -Path src\copier.yml @' drive: type: str default: "C:" when: false '@ echo "bar" > "src{{ pathjoin(drive, 'Users', '', 'Temp', 'test-copier-vulnerability', 'forbidden.txt') }}" uvx --from copier python -O -m copier copy --overwrite src dst cat forbidden.txt ```

Severity

6.9 (Medium)


                  
                    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

Show details on source website

JSON

To clipboard

{
  "affected": [
    {
      "package": {
        "ecosystem": "PyPI",
        "name": "copier"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "7.1.0"
            },
            {
              "fixed": "9.9.1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2025-55214"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-22"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2025-08-18T21:01:07Z",
    "nvd_published_at": "2025-08-18T17:15:30Z",
    "severity": "MODERATE"
  },
  "details": "### Impact\n\nCopier suggests that it\u0027s safe to generate a project from a safe template, i.e. one that doesn\u0027t 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 write files outside the destination path where a project shall be generated or updated. This is possible when rendering a [generated directory structure](https://copier.readthedocs.io/en/stable/configuring/#generating-a-directory-structure) whose rendered path is either a relative parent path or an absolute path. Constructing such paths is possible using Copier\u0027s builtin `pathjoin` Jinja filter and its builtin `_copier_conf.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\u0027s write permissions), e.g., to cause havoc.\n\n#### Write access via generated relative path\n\nReproducible example:\n\n```shell\necho \"foo\" \u003e forbidden.txt\nmkdir src/\necho \"bar\" \u003e \"src/{{ pathjoin(\u0027..\u0027, \u0027forbidden.txt\u0027) }}\"\nuvx copier copy src/ dst/\ncat forbidden.txt\n```\n\n#### Write access via generated absolute path\n\nReproducible example:\n\n- POSIX:\n\n    ```shell\n    # Assumption: The current working directory is `/tmp/test-copier-vulnerability/`\n    echo \"foo\" \u003e forbidden.txt\n    mkdir src/\n    echo \"bar\" \u003e \"src/{{ pathjoin(_copier_conf.sep, \u0027tmp\u0027, \u0027test-copier-vulnerability\u0027, \u0027forbidden.txt\u0027) }}\"\n    uvx --from copier python -O -m copier copy --overwrite src/ dst/\n    cat forbidden.txt\n    ```\n\n- Windows (PowerShell):\n\n    ```powershell\n    # Assumption: The current working directory is `C:\\Users\\\u003cuser\u003e\\Temp\\test-copier-vulnerability`\n    echo \"foo\" \u003e forbidden.txt\n    mkdir src\n    Set-Content -Path src\\copier.yml @\u0027\n    drive:\n      type: str\n      default: \"C:\"\n      when: false\n    \u0027@\n    echo \"bar\" \u003e \"src\\{{ pathjoin(drive, \u0027Users\u0027, \u0027\u003cuser\u003e\u0027, \u0027Temp\u0027, \u0027test-copier-vulnerability\u0027, \u0027forbidden.txt\u0027) }}\"\n    uvx --from copier python -O -m copier copy --overwrite src dst\n    cat forbidden.txt\n    ```\n\nThis scenario is slightly less severe, as Copier has a few [assertions of the destination path being relative](https://github.com/copier-org/copier/blob/d106ea543fd26e1ac1b9a3dcef3e99cc70fdf57c/copier/_main.py#L747) which would typically be raised. But `python -O` (or `PYTHONOPTIMIZE=x`) removes asserts, so these guards may be ineffective. In addition, this scenario will prompt for overwrite confirmation or require the `--overwrite` flag for non-interactive mode; yet malicious file writes might go unnoticed.",
  "id": "GHSA-p7q8-grrj-3m8w",
  "modified": "2025-08-18T21:01:07Z",
  "published": "2025-08-18T21:01:07Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/copier-org/copier/security/advisories/GHSA-p7q8-grrj-3m8w"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2025-55214"
    },
    {
      "type": "WEB",
      "url": "https://github.com/copier-org/copier/commit/fdbc0167cc22780b497e4db176feaf6f024757d6"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/copier-org/copier"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "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",
      "type": "CVSS_V4"
    }
  ],
  "summary": "Copier\u0027s safe template has filesystem write access outside destination path"
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Detection rules are retrieved from Rulezet.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.

Related by attack behaviour

Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.

PYSEC-2026-1273

Impact

Write access via generated relative path

Write access via generated absolute path

Assumption: The current working directory is `/tmp/test-copier-vulnerability/`

Assumption: The current working directory is `C:\Users\<user>\Temp\test-copier-vulnerability`

Assumption: The current working directory is `/tmp/test-copier-vulnerability/`

Assumption: The current working directory is `C:\Users\<user>\Temp\test-copier-vulnerability`

Assumption: The current working directory is `/tmp/test-copier-vulnerability/`

Assumption: The current working directory is `C:\Users\<user>\Temp\test-copier-vulnerability`

Tags

Sightings

Nomenclature

Related by attack behaviour

Action not permitted

PYSEC-2026-1273

Impact

Write access via generated relative path

Write access via generated absolute path

Assumption: The current working directory is /tmp/test-copier-vulnerability/

Assumption: The current working directory is C:\Users\<user>\Temp\test-copier-vulnerability

BREW-COPIER-CVE-2025-55214 (GHSA-P7Q8-GRRJ-3M8W)

Impact

Write access via generated relative path

Write access via generated absolute path

Assumption: The current working directory is /tmp/test-copier-vulnerability/

Assumption: The current working directory is C:\Users\<user>\Temp\test-copier-vulnerability

CVE-2025-55214 (GCVE-0-2025-55214)

GHSA-P7Q8-GRRJ-3M8W

Impact

Write access via generated relative path

Write access via generated absolute path

Assumption: The current working directory is /tmp/test-copier-vulnerability/

Assumption: The current working directory is C:\Users\<user>\Temp\test-copier-vulnerability

Tags

Sightings

Nomenclature

Related by attack behaviour

Assumption: The current working directory is `/tmp/test-copier-vulnerability/`

Assumption: The current working directory is `C:\Users\<user>\Temp\test-copier-vulnerability`

Assumption: The current working directory is `/tmp/test-copier-vulnerability/`

Assumption: The current working directory is `C:\Users\<user>\Temp\test-copier-vulnerability`

Assumption: The current working directory is `/tmp/test-copier-vulnerability/`

Assumption: The current working directory is `C:\Users\<user>\Temp\test-copier-vulnerability`