Vulnerability-Lookup

PYSEC-2026-2134

Vulnerability from pysec - Published: 2026-04-02 19:21 - Updated: 2026-07-13 05:48

Details

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.

Severity

4.4 (Medium)


                  
                    CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N

Impacted products

Name	purl
copier	pkg:pypi/copier

Aliases

JSON

To clipboard

{
  "affected": [
    {
      "ecosystem_specific": {},
      "package": {
        "ecosystem": "PyPI",
        "name": "copier",
        "purl": "pkg:pypi/copier"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "9.14.1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "2.0.0",
        "2.0.1",
        "2.1.0",
        "2.2.1",
        "2.2.2",
        "2.2.3",
        "2.3",
        "2.3.1",
        "2.3.2",
        "2.3.3",
        "2.4.0",
        "2.4.1",
        "2.4.2",
        "2.5.0",
        "2.5.1",
        "3.0.0a3",
        "3.0.0a5",
        "3.0.0a6",
        "3.0.0a7",
        "3.0.0a8",
        "3.0.0b1",
        "3.0.1",
        "3.0.2",
        "3.0.3",
        "3.0.4",
        "3.0.5",
        "3.0.6",
        "3.1.0",
        "3.2.0",
        "4.0.0",
        "4.0.1",
        "4.0.2",
        "4.1.0",
        "5.0.0",
        "5.1.0",
        "6.0.0",
        "6.0.0a0",
        "6.0.0a2",
        "6.0.0a3",
        "6.0.0a4",
        "6.0.0a5",
        "6.0.0a6",
        "6.0.0a7",
        "6.0.0a9",
        "6.0.0b0",
        "6.1.0",
        "6.2.0",
        "7.0.1",
        "7.1.0",
        "7.1.0a0",
        "7.2.0",
        "8.0.0",
        "8.1.0",
        "8.2.0",
        "8.3.0",
        "9.0.1",
        "9.1.0",
        "9.1.1",
        "9.10.0",
        "9.10.1",
        "9.10.2",
        "9.10.3",
        "9.11.0",
        "9.11.1",
        "9.11.2",
        "9.11.3",
        "9.12.0",
        "9.13.0",
        "9.13.1",
        "9.14.0",
        "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",
        "9.9.1"
      ]
    }
  ],
  "aliases": [
    "CVE-2026-34726",
    "GHSA-85v3-4m8g-hrh6"
  ],
  "details": "Copier is a library and CLI app for rendering project templates. Prior to version 9.14.1, Copier\u0027s _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.",
  "id": "PYSEC-2026-2134",
  "modified": "2026-07-13T05:48:21.008558Z",
  "published": "2026-04-02T19:21:32.320Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://github.com/copier-org/copier/releases/tag/v9.14.1"
    },
    {
      "type": "FIX",
      "url": "https://github.com/copier-org/copier/commit/cb80a3ffc9c3787de3ed837e04ca29a0ff8ca3df"
    },
    {
      "type": "EVIDENCE",
      "url": "https://github.com/copier-org/copier/security/advisories/GHSA-85v3-4m8g-hrh6"
    }
  ],
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N",
      "type": "CVSS_V3"
    }
  ]
}

CVE-2026-34726 (GCVE-0-2026-34726)

Vulnerability from cvelistv5 – Published: 2026-04-02 18:07 – Updated: 2026-04-03 16:16

Title

Copier `_subdirectory` allows template root escape via parent-directory traversal

Summary

Severity

4.4 (Medium)


                        
                          CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N

SSVC

Exploitation: poc Automatable: no Technical Impact: partial

CISA Coordinator (v2.0.3)

CWE

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

Assigner

GitHub_M

References

3 references

URL	Tags
https://github.com/copier-org/copier/security/adv…	x_refsource_CONFIRM
https://github.com/copier-org/copier/commit/cb80a…	x_refsource_MISC
https://github.com/copier-org/copier/releases/tag…	x_refsource_MISC

Impacted products

1 product

Vendor	Product	Version
copier-org	copier	Affected: < 9.14.1

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-34726",
                "options": [
                  {
                    "Exploitation": "poc"
                  },
                  {
                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-04-03T16:15:43.192383Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-04-03T16:16:03.275Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "references": [
          {
            "tags": [
              "exploit"
            ],
            "url": "https://github.com/copier-org/copier/security/advisories/GHSA-85v3-4m8g-hrh6"
          }
        ],
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "product": "copier",
          "vendor": "copier-org",
          "versions": [
            {
              "status": "affected",
              "version": "\u003c 9.14.1"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "Copier is a library and CLI app for rendering project templates. Prior to version 9.14.1, Copier\u0027s _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."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "attackComplexity": "LOW",
            "attackVector": "LOCAL",
            "availabilityImpact": "NONE",
            "baseScore": 4.4,
            "baseSeverity": "MEDIUM",
            "confidentialityImpact": "LOW",
            "integrityImpact": "LOW",
            "privilegesRequired": "NONE",
            "scope": "UNCHANGED",
            "userInteraction": "REQUIRED",
            "vectorString": "CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N",
            "version": "3.1"
          }
        }
      ],
      "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": "2026-04-02T18:07:35.517Z",
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "shortName": "GitHub_M"
      },
      "references": [
        {
          "name": "https://github.com/copier-org/copier/security/advisories/GHSA-85v3-4m8g-hrh6",
          "tags": [
            "x_refsource_CONFIRM"
          ],
          "url": "https://github.com/copier-org/copier/security/advisories/GHSA-85v3-4m8g-hrh6"
        },
        {
          "name": "https://github.com/copier-org/copier/commit/cb80a3ffc9c3787de3ed837e04ca29a0ff8ca3df",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/copier-org/copier/commit/cb80a3ffc9c3787de3ed837e04ca29a0ff8ca3df"
        },
        {
          "name": "https://github.com/copier-org/copier/releases/tag/v9.14.1",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/copier-org/copier/releases/tag/v9.14.1"
        }
      ],
      "source": {
        "advisory": "GHSA-85v3-4m8g-hrh6",
        "discovery": "UNKNOWN"
      },
      "title": "Copier `_subdirectory` allows template root escape via parent-directory traversal"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
    "assignerShortName": "GitHub_M",
    "cveId": "CVE-2026-34726",
    "datePublished": "2026-04-02T18:07:35.517Z",
    "dateReserved": "2026-03-30T18:41:20.753Z",
    "dateUpdated": "2026-04-03T16:16:03.275Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

GHSA-85V3-4M8G-HRH6

Vulnerability from github – Published: 2026-04-01 22:28 – Updated: 2026-04-06 17:32

Summary

Copier `_subdirectory` allows template root escape via parent-directory traversal

Details

Summary

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.

Details

The relevant code path is:

the template defines _subdirectory
Copier renders that string
template_copy_root returns self.template.local_abspath / subdir
Copier walks that directory as the template root

Relevant code:

The effective sink is:

subdir = self._render_string(self.template.subdirectory) or ""
return self.template.local_abspath / subdir

There is no check that the resulting path stays inside the template directory.

The documentation for _subdirectory describes it as:

Subdirectory to use as the template root when generating a project.

and explains it as a way to separate template metadata from template source code:

https://github.com/copier-org/copier/blob/7aa7021bd73797c982492bac3535515d4484fdb7/docs/configuring.md#L1582-L1646

That description fits values like template or poetry, but not ...

PoC

PoC 1: `_subdirectory: ..` escapes to the parent directory

mkdir -p root/template dst
echo 'loot' > root/loot.txt
printf '%s\n' '_subdirectory: ..' > root/template/copier.yml

copier copy --overwrite root/template dst
find dst -maxdepth 3 -type f | sort
cat dst/loot.txt

Expected output includes:

dst/loot.txt
dst/template/copier.yml
loot

This shows Copier is rendering from root/ rather than from root/template/.

Impact

If a user runs Copier on an untrusted template, that template can change the effective template root and make Copier render files from outside the intended template directory.

Practical impact:

template-root escape via ..
rendering of parent-directory files that were not meant to be part of the template
possible without --UNSAFE

Severity

4.4 (Medium)


                  
                    CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N

Show details on source website

JSON

To clipboard

{
  "affected": [
    {
      "package": {
        "ecosystem": "PyPI",
        "name": "copier"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "9.14.1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-34726"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-22"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-04-01T22:28:49Z",
    "nvd_published_at": "2026-04-02T19:21:32Z",
    "severity": "MODERATE"
  },
  "details": "### Summary\n\nCopier\u0027s `_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.\n\nAs a result, a template can escape its own directory and make Copier render files from the parent directory without `--UNSAFE`.\n\n### Details\n\nThe relevant code path is:\n\n1. the template defines `_subdirectory`\n2. Copier renders that string\n3. `template_copy_root` returns `self.template.local_abspath / subdir`\n4. Copier walks that directory as the template root\n\nRelevant code:\n\n- \u003chttps://github.com/copier-org/copier/blob/7aa7021bd73797c982492bac3535515d4484fdb7/copier/_main.py#L1056-L1062\u003e\n- \u003chttps://github.com/copier-org/copier/blob/7aa7021bd73797c982492bac3535515d4484fdb7/copier/_template.py#L504-L513\u003e\n\nThe effective sink is:\n\n```python\nsubdir = self._render_string(self.template.subdirectory) or \"\"\nreturn self.template.local_abspath / subdir\n```\n\nThere is no check that the resulting path stays inside the template directory.\n\nThe documentation for `_subdirectory` describes it as:\n\n\u003e Subdirectory to use as the template root when generating a project.\n\nand explains it as a way to separate template metadata from template source code:\n\n\u003chttps://github.com/copier-org/copier/blob/7aa7021bd73797c982492bac3535515d4484fdb7/docs/configuring.md#L1582-L1646\u003e\n\nThat description fits values like `template` or `poetry`, but not `..`.\n\n### PoC\n\n#### PoC 1: `_subdirectory: ..` escapes to the parent directory\n\n```sh\nmkdir -p root/template dst\necho \u0027loot\u0027 \u003e root/loot.txt\nprintf \u0027%s\\n\u0027 \u0027_subdirectory: ..\u0027 \u003e root/template/copier.yml\n\ncopier copy --overwrite root/template dst\nfind dst -maxdepth 3 -type f | sort\ncat dst/loot.txt\n```\n\nExpected output includes:\n\n```text\ndst/loot.txt\ndst/template/copier.yml\nloot\n```\n\nThis shows Copier is rendering from `root/` rather than from `root/template/`.\n\n### Impact\n\nIf a user runs Copier on an untrusted template, that template can change the effective template root and make Copier render files from outside the intended template directory.\n\nPractical impact:\n\n- template-root escape via `..`\n- rendering of parent-directory files that were not meant to be part of the template\n- possible without `--UNSAFE`",
  "id": "GHSA-85v3-4m8g-hrh6",
  "modified": "2026-04-06T17:32:29Z",
  "published": "2026-04-01T22:28:49Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/copier-org/copier/security/advisories/GHSA-85v3-4m8g-hrh6"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-34726"
    },
    {
      "type": "WEB",
      "url": "https://github.com/copier-org/copier/commit/cb80a3ffc9c3787de3ed837e04ca29a0ff8ca3df"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/copier-org/copier"
    },
    {
      "type": "WEB",
      "url": "https://github.com/copier-org/copier/releases/tag/v9.14.1"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "Copier `_subdirectory` allows template root escape via parent-directory traversal"
}

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.

Action not permitted

PYSEC-2026-2134

CVE-2026-34726 (GCVE-0-2026-34726)

GHSA-85V3-4M8G-HRH6

Summary

Details

PoC

PoC 1: _subdirectory: .. escapes to the parent directory

Impact

Tags

Sightings

Nomenclature

PoC 1: `_subdirectory: ..` escapes to the parent directory