Vulnerability-Lookup

GHSA-37W4-HWHX-4RC4

Vulnerability from github – Published: 2026-05-05 20:53 – Updated: 2026-05-21 00:41

Summary

JupyterLab has an Extension Manager API/GUI Policy Discrepancy, allowing 3rd party (malicious) extensions install via POST request

Details

The allow-list of extensions that can be installed from PyPI Extension Manager (allowed_extensions_uris) is not correctly enforced by JupyterLab prior to 4.5.7. The PyPI Extension Manager was not contained to packages listed on the default PyPI index.

This has security implications for deployments that: - have allow-listed specific extensions with aim to prevent users from installing packages - have the kernel and terminals disabled or delegated to remote hosts (thus no access to install packages in the single-user server environment) - have multi-tenant deployments that is not configured for untrusted users (as per documented on JupyterHub https://jupyterhub.readthedocs.io/en/5.2.1/explanation/websecurity.html) - have the (default) PyPI Extension Manager enabled

Impact

An authenticated attacker - such as a student in a shared JupyterHub environment or a user in a multi-tenant JupyterLab deployment - can escalate their privileges. This might allow for data exfiltration, lateral movement within the network, and persistent compromise of the server infrastructure.

Patches

JupyterLab v4.5.7 contains the patch.

Users of applications that depend on JupyterLab, such as Notebook v7+, should update jupyterlab package too.

Workarounds

Switch to read-only extension manager by adding the following command line option:

--LabApp.extension_manager=readonly

or the following traitlet:

c.LabApp.extension_manager = 'readonly'

You can confirm that the read-only manager is in use from GUI:

Note: configuration of a PyPI proxy with allow-listed packages is not sufficient to protect from this vulnerability.

References

allow-list https://jupyterlab.readthedocs.io/en/stable/user/extensions.html#listing-configuration
https://jupyterhub.readthedocs.io/en/5.2.1/explanation/websecurity.html
https://jupyterlab.readthedocs.io/en/latest/user/extensions.html#extension-manager-implementations

Severity ?

8.8 (High)


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

Show details on source website

JSON

To clipboard

{
  "affected": [
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 4.5.6"
      },
      "package": {
        "ecosystem": "PyPI",
        "name": "jupyterlab"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "4.0.0"
            },
            {
              "fixed": "4.5.7"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-42266"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-20",
      "CWE-88",
      "CWE-602"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-05-05T20:53:18Z",
    "nvd_published_at": "2026-05-13T16:16:47Z",
    "severity": "HIGH"
  },
  "details": "The allow-list of extensions that can be installed from PyPI Extension Manager (`allowed_extensions_uris`) is not correctly enforced by JupyterLab prior to 4.5.7. The PyPI Extension Manager was not contained to packages listed on the default PyPI index.\n\nThis has security implications for deployments that:\n- have allow-listed specific extensions with aim to prevent users from installing packages\n- have the kernel and terminals disabled or delegated to remote hosts (thus no access to install packages in the single-user server environment)\n- have multi-tenant deployments that is not configured for untrusted users (as per documented on JupyterHub https://jupyterhub.readthedocs.io/en/5.2.1/explanation/websecurity.html)\n- have the (default) PyPI Extension Manager enabled\n\n### Impact\n\nAn authenticated attacker - such as a student in a shared JupyterHub environment or a user in a multi-tenant JupyterLab deployment - can escalate their privileges. This might allow for data exfiltration, lateral movement within the network, and persistent compromise of the server infrastructure.\n\n### Patches\n\nJupyterLab [`v4.5.7`](https://github.com/jupyterlab/jupyterlab/releases/tag/v4.5.7) contains the patch.\n\nUsers of applications that depend on JupyterLab, such as Notebook v7+, should update `jupyterlab` package too.\n\n### Workarounds\n\nSwitch to read-only extension manager by adding the following command line option:\n\n```bash\n--LabApp.extension_manager=readonly\n```\n\nor the following traitlet:\n\n```python\nc.LabApp.extension_manager = \u0027readonly\u0027\n```\n\nYou can confirm that the read-only manager is in use from GUI:\n\n\u003cimg width=\"293\" height=\"293\" alt=\"image\" src=\"https://github.com/user-attachments/assets/8016c809-633e-4ed0-a5bc-6bc4793caa0f\" /\u003e\n\nNote: configuration of a PyPI proxy with allow-listed packages is not sufficient to protect from this vulnerability.\n\n### References\n\n- allow-list https://jupyterlab.readthedocs.io/en/stable/user/extensions.html#listing-configuration\n- https://jupyterhub.readthedocs.io/en/5.2.1/explanation/websecurity.html\n- https://jupyterlab.readthedocs.io/en/latest/user/extensions.html#extension-manager-implementations",
  "id": "GHSA-37w4-hwhx-4rc4",
  "modified": "2026-05-21T00:41:39Z",
  "published": "2026-05-05T20:53:18Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/jupyterlab/jupyterlab/security/advisories/GHSA-37w4-hwhx-4rc4"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-42266"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/jupyterlab/jupyterlab"
    },
    {
      "type": "WEB",
      "url": "https://github.com/jupyterlab/jupyterlab/releases/tag/v4.5.7"
    },
    {
      "type": "WEB",
      "url": "https://jupyterhub.readthedocs.io/en/5.2.1/explanation/websecurity.html"
    },
    {
      "type": "WEB",
      "url": "https://jupyterlab.readthedocs.io/en/latest/user/extensions.html#extension-manager-implementations"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ],
  "summary": "JupyterLab has an Extension Manager API/GUI Policy Discrepancy, allowing 3rd party (malicious) extensions install via POST request"
}

CVE-2026-42266 (GCVE-0-2026-42266)

Vulnerability from cvelistv5 – Published: 2026-05-13 15:08 – Updated: 2026-05-21 00:41

Title

JupyterLab has an Extension Manager API/GUI Policy Discrepancy allowing 3rd party (malicious) extensions install via POST request.

Summary

JupyterLab is an extensible environment for interactive and reproducible computing, based on the Jupyter Notebook Architecture. From 4.0.0 to 4.5.6, the allow-list of extensions that can be installed from PyPI Extension Manager (allowed_extensions_uris) is not correctly enforced by JupyterLab. The PyPI Extension Manager was not contained to packages listed on the default PyPI index. This vulnerability is fixed in 4.5.7.

Severity ?

8.8 (High)


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

CWE

CWE-88 - Improper Neutralization of Argument Delimiters in a Command ('Argument Injection')
CWE-602 - Client-Side Enforcement of Server-Side Security

Assigner

GitHub_M

References

4 references

URL	Tags
https://github.com/jupyterlab/jupyterlab/security…	x_refsource_CONFIRM
https://github.com/jupyterlab/jupyterlab/releases…	x_refsource_MISC
https://jupyterhub.readthedocs.io/en/5.2.1/explan…	x_refsource_MISC
https://jupyterlab.readthedocs.io/en/latest/user/…	x_refsource_MISC

Impacted products

1 product

Vendor	Product	Version
jupyterlab	jupyterlab	Affected: >= 4.0.0, < 4.5.7

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-42266",
                "options": [
                  {
                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "total"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-05-13T00:00:00+00:00",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-05-14T03:56:38.179Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "product": "jupyterlab",
          "vendor": "jupyterlab",
          "versions": [
            {
              "status": "affected",
              "version": "\u003e= 4.0.0, \u003c 4.5.7"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "JupyterLab is an extensible environment for interactive and reproducible computing, based on the Jupyter Notebook Architecture. From 4.0.0 to 4.5.6, the allow-list of extensions that can be installed from PyPI Extension Manager (allowed_extensions_uris) is not correctly enforced by JupyterLab. The PyPI Extension Manager was not contained to packages listed on the default PyPI index. This vulnerability is fixed in 4.5.7."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "attackComplexity": "LOW",
            "attackVector": "NETWORK",
            "availabilityImpact": "HIGH",
            "baseScore": 8.8,
            "baseSeverity": "HIGH",
            "confidentialityImpact": "HIGH",
            "integrityImpact": "HIGH",
            "privilegesRequired": "LOW",
            "scope": "UNCHANGED",
            "userInteraction": "NONE",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          }
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-88",
              "description": "CWE-88: Improper Neutralization of Argument Delimiters in a Command (\u0027Argument Injection\u0027)",
              "lang": "en",
              "type": "CWE"
            }
          ]
        },
        {
          "descriptions": [
            {
              "cweId": "CWE-602",
              "description": "CWE-602: Client-Side Enforcement of Server-Side Security",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-05-21T00:41:24.140Z",
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "shortName": "GitHub_M"
      },
      "references": [
        {
          "name": "https://github.com/jupyterlab/jupyterlab/security/advisories/GHSA-37w4-hwhx-4rc4",
          "tags": [
            "x_refsource_CONFIRM"
          ],
          "url": "https://github.com/jupyterlab/jupyterlab/security/advisories/GHSA-37w4-hwhx-4rc4"
        },
        {
          "name": "https://github.com/jupyterlab/jupyterlab/releases/tag/v4.5.7",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/jupyterlab/jupyterlab/releases/tag/v4.5.7"
        },
        {
          "name": "https://jupyterhub.readthedocs.io/en/5.2.1/explanation/websecurity.html",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://jupyterhub.readthedocs.io/en/5.2.1/explanation/websecurity.html"
        },
        {
          "name": "https://jupyterlab.readthedocs.io/en/latest/user/extensions.html#extension-manager-implementations",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://jupyterlab.readthedocs.io/en/latest/user/extensions.html#extension-manager-implementations"
        }
      ],
      "source": {
        "advisory": "GHSA-37w4-hwhx-4rc4",
        "discovery": "UNKNOWN"
      },
      "title": "JupyterLab has an Extension Manager API/GUI Policy Discrepancy allowing 3rd party (malicious) extensions install via POST request."
    }
  },
  "cveMetadata": {
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
    "assignerShortName": "GitHub_M",
    "cveId": "CVE-2026-42266",
    "datePublished": "2026-05-13T15:08:49.846Z",
    "dateReserved": "2026-04-26T11:53:27.706Z",
    "dateUpdated": "2026-05-21T00:41:24.140Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

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

GHSA-37W4-HWHX-4RC4

Impact

Patches

Workarounds

References

CVE-2026-42266 (GCVE-0-2026-42266)

Tags

Sightings

Nomenclature