Vulnerability-Lookup

CVE-2026-40171 (GCVE-0-2026-40171)

Vulnerability from cvelistv5 – Published: 2026-05-06 19:36 – Updated: 2026-05-08 03:55

Title

Jupyter Notebook and JupyterLab token theft via stored XSS in help command linker

Summary

In Jupyter Notebook versions 7.0.0 through 7.5.5, JupyterLab versions 4.5.6 and earlier, and the corresponding @jupyter-notebook/help-extension and @jupyterlab/help-extension packages before 7.5.6 and 4.5.7, a stored cross-site scripting issue in the help command linker can be chained with attacker-controlled notebook content to steal authentication tokens with a single click. An attacker can craft a malicious notebook file containing elements that appear indistinguishable from legitimate controls and trigger execution when a user interacts with them. Successful exploitation allows theft of the user's authentication token and complete takeover of the Jupyter session through the REST API, including reading files, creating or modifying files, accessing kernels to execute arbitrary code, and creating terminals for shell access. This issue has been fixed in Notebook 7.5.6, JupyterLab 4.5.7, @jupyter-notebook/help-extension 7.5.6, and @jupyterlab/help-extension 4.5.7. As a workaround, disable the affected help extensions or set allowCommandLinker to false in the sanitizer configuration.

Severity ?

8.4 (High)


                        
                          CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:A/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

CWE

CWE-79 - Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

Assigner

GitHub_M

References

URL

Tags

https://github.com/jupyter/notebook/security/advi…

x_refsource_CONFIRM

Impacted products

Vendor

Product

Version

jupyter

notebook

Affected: >=7.0.0, <= 7.5.5

jupyterlab	help-extension	Affected: <=4.5.6
jupyterlab	jupyterlab	Affected: <= 4.5.6
jupyter-notebook	help-extension	Affected: >=7.0.0,<= 7.5.5

Show details on NVD website

JSON

To clipboard

{
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                "id": "CVE-2026-40171",
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FKIE_CVE-2026-40171

Vulnerability from fkie_nvd - Published: 2026-05-06 20:16 - Updated: 2026-05-07 15:07

Severity ?

8.4 (High) - CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:A/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

Summary

References

	URL	Tags
	security-advisories@github.com	https://github.com/jupyter/notebook/security/advisories/GHSA-rch3-82jr-f9w9

Impacted products

	Vendor	Product	Version

JSON

To clipboard

{
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In Jupyter Notebook versions 7.0.0 through 7.5.5, JupyterLab versions 4.5.6 and earlier, and the corresponding @jupyter-notebook/help-extension and @jupyterlab/help-extension packages before 7.5.6 and 4.5.7, a stored cross-site scripting issue in the help command linker can be chained with attacker-controlled notebook content to steal authentication tokens with a single click.\n\nAn attacker can craft a malicious notebook file containing elements that appear indistinguishable from legitimate controls and trigger execution when a user interacts with them. Successful exploitation allows theft of the user\u0027s authentication token and complete takeover of the Jupyter session through the REST API, including reading files, creating or modifying files, accessing kernels to execute arbitrary code, and creating terminals for shell access. This issue has been fixed in Notebook 7.5.6, JupyterLab 4.5.7, @jupyter-notebook/help-extension 7.5.6, and @jupyterlab/help-extension 4.5.7. As a workaround, disable the affected help extensions or set allowCommandLinker to false in the sanitizer configuration."
    }
  ],
  "id": "CVE-2026-40171",
  "lastModified": "2026-05-07T15:07:32.390",
  "metrics": {
    "cvssMetricV40": [
      {
        "cvssData": {
          "Automatable": "NOT_DEFINED",
          "Recovery": "NOT_DEFINED",
          "Safety": "NOT_DEFINED",
          "attackComplexity": "LOW",
          "attackRequirements": "NONE",
          "attackVector": "NETWORK",
          "availabilityRequirement": "NOT_DEFINED",
          "baseScore": 8.4,
          "baseSeverity": "HIGH",
          "confidentialityRequirement": "NOT_DEFINED",
          "exploitMaturity": "NOT_DEFINED",
          "integrityRequirement": "NOT_DEFINED",
          "modifiedAttackComplexity": "NOT_DEFINED",
          "modifiedAttackRequirements": "NOT_DEFINED",
          "modifiedAttackVector": "NOT_DEFINED",
          "modifiedPrivilegesRequired": "NOT_DEFINED",
          "modifiedSubAvailabilityImpact": "NOT_DEFINED",
          "modifiedSubConfidentialityImpact": "NOT_DEFINED",
          "modifiedSubIntegrityImpact": "NOT_DEFINED",
          "modifiedUserInteraction": "NOT_DEFINED",
          "modifiedVulnAvailabilityImpact": "NOT_DEFINED",
          "modifiedVulnConfidentialityImpact": "NOT_DEFINED",
          "modifiedVulnIntegrityImpact": "NOT_DEFINED",
          "privilegesRequired": "HIGH",
          "providerUrgency": "NOT_DEFINED",
          "subAvailabilityImpact": "NONE",
          "subConfidentialityImpact": "NONE",
          "subIntegrityImpact": "NONE",
          "userInteraction": "ACTIVE",
          "valueDensity": "NOT_DEFINED",
          "vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:A/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X",
          "version": "4.0",
          "vulnAvailabilityImpact": "HIGH",
          "vulnConfidentialityImpact": "HIGH",
          "vulnIntegrityImpact": "HIGH",
          "vulnerabilityResponseEffort": "NOT_DEFINED"
        },
        "source": "security-advisories@github.com",
        "type": "Secondary"
      }
    ]
  },
  "published": "2026-05-06T20:16:31.857",
  "references": [
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/jupyter/notebook/security/advisories/GHSA-rch3-82jr-f9w9"
    }
  ],
  "sourceIdentifier": "security-advisories@github.com",
  "vulnStatus": "Awaiting Analysis",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-79"
        }
      ],
      "source": "security-advisories@github.com",
      "type": "Primary"
    }
  ]
}

GHSA-RCH3-82JR-F9W9

Vulnerability from github – Published: 2026-04-30 17:25 – Updated: 2026-05-08 19:26

Summary

Jupyter Notebook Vulnerable to Authentication Token Theft via CommandLinker XSS

Details

Impact

A stored Cross-Site Scripting (XSS) vulnerability in Jupyter Notebook allows attackers to steal authentication tokens from users who open malicious notebook files and interact with elements that the attacker can make look indistinguishable from legitimate controls (single click interaction).

The vulnerability enables complete account takeover through the Jupyter REST API, allowing the attacker to: 1. Read all files 2. Modify/create files 3. Access running kernels and execute arbitrary code 4. Create terminals for shell access

Patches

Jupyter Notebook 7.5.6 and JupyterLab 4.5.7 include patches for this vulnerability.

Workarounds

The help extension can be disabled via CLI:

jupyter labextension disable @jupyter-notebook/help-extension
jupyter labextension disable @jupyterlab/help-extension

Hardening

The patched versions include a toggle to disable the command linker functionality altogether, for example via overrides.json:

{
  "@jupyterlab/apputils-extension:sanitizer": {
    "allowCommandLinker": false
  }
}

Resources

https://jupyterlab.readthedocs.io/en/latest/user/commands.html#commands-in-markdown-output-and-files

Acknowledgments

Reported by Daniel Teixeira - NVIDIA AI Red Team

Severity ?

8.4 (High)


                  
                    CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:A/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

Show details on source website

JSON

To clipboard

{
  "affected": [
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 7.5.5"
      },
      "package": {
        "ecosystem": "npm",
        "name": "@jupyter-notebook/help-extension"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "7.0.0"
            },
            {
              "fixed": "7.5.6"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 7.5.5"
      },
      "package": {
        "ecosystem": "PyPI",
        "name": "notebook"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "7.0.0"
            },
            {
              "fixed": "7.5.6"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 4.5.6"
      },
      "package": {
        "ecosystem": "PyPI",
        "name": "jupyterlab"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "4.5.7"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 4.5.6"
      },
      "package": {
        "ecosystem": "npm",
        "name": "@jupyterlab/help-extension"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "4.5.7"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-40171"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-601",
      "CWE-79"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-04-30T17:25:47Z",
    "nvd_published_at": "2026-05-06T20:16:31Z",
    "severity": "HIGH"
  },
  "details": "### Impact\n\nA stored Cross-Site Scripting (XSS) vulnerability in Jupyter Notebook allows attackers to steal authentication tokens from users who open malicious notebook files and interact with elements that the attacker can make look indistinguishable from legitimate controls (single click interaction).\n\nThe vulnerability enables complete account takeover through the Jupyter REST API, allowing the attacker to:\n1. Read all files\n2. Modify/create files\n3. Access running kernels and execute arbitrary code\n4. Create terminals for shell access\n\n### Patches\n\nJupyter Notebook 7.5.6 and JupyterLab 4.5.7 include patches for this vulnerability.\n\n### Workarounds\n\nThe help extension can be disabled via CLI:\n\n```\njupyter labextension disable @jupyter-notebook/help-extension\njupyter labextension disable @jupyterlab/help-extension\n```\n\n### Hardening\n\nThe patched versions include a toggle to disable the command linker functionality altogether, for example via `overrides.json`:\n\n```json\n{\n  \"@jupyterlab/apputils-extension:sanitizer\": {\n    \"allowCommandLinker\": false\n  }\n}\n```\n\n### Resources\n\n- https://jupyterlab.readthedocs.io/en/latest/user/commands.html#commands-in-markdown-output-and-files\n\n### Acknowledgments\n\nReported by Daniel Teixeira - NVIDIA AI Red Team",
  "id": "GHSA-rch3-82jr-f9w9",
  "modified": "2026-05-08T19:26:04Z",
  "published": "2026-04-30T17:25:47Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/jupyter/notebook/security/advisories/GHSA-rch3-82jr-f9w9"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-40171"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/jupyter/notebook"
    },
    {
      "type": "WEB",
      "url": "https://jupyterlab.readthedocs.io/en/latest/user/commands.html#commands-in-markdown-output-and-files"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:A/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "Jupyter Notebook Vulnerable to Authentication Token Theft via CommandLinker XSS"
}

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

CVE-2026-40171 (GCVE-0-2026-40171)

FKIE_CVE-2026-40171

GHSA-RCH3-82JR-F9W9

Impact

Patches

Workarounds

Hardening

Resources

Acknowledgments

Tags

Sightings

Nomenclature