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PYSEC-2026-1480

Vulnerability from pysec - Published: 2026-07-07 11:45 - Updated: 2026-07-07 17:24
VLAI
Details

Impact

Affected configurations:

  • Single-origin JupyterHub deployments
  • JupyterHub deployments with user-controlled applications running on subdomains or peer subdomains of either the Hub or a single-user server.

By tricking a user into visiting a malicious subdomain, the attacker can achieve an XSS directly affecting the former's session. More precisely, in the context of JupyterHub, this XSS could achieve the following:

  • Full access to JupyterHub API and user's single-user server, e.g.
  • Create and exfiltrate an API Token
  • Exfiltrate all files hosted on the user's single-user server: notebooks, images, etc.
  • Install malicious extensions. They can be used as a backdoor to silently regain access to victim's session anytime.

Patches

To prevent cookie-tossing:

  • Upgrade to JupyterHub 4.1 (both hub and user environment)
  • enable per-user domains via c.JupyterHub.subdomain_host = "https://mydomain.example.org"
  • set c.JupyterHub.cookie_host_prefix_enabled = True to enable domain-locked cookies

or, if available (applies to earlier JupyterHub versions):

  • deploy jupyterhub on its own domain, not shared with any other services
  • enable per-user domains via c.JupyterHub.subdomain_host = "https://mydomain.example.org"
Severity
8.1 (High)
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N
Impacted products
Name purl
jupyterhub pkg:pypi/jupyterhub
Aliases
To clipboard 

{
  "affected": [
    {
      "package": {
        "ecosystem": "PyPI",
        "name": "jupyterhub",
        "purl": "pkg:pypi/jupyterhub"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "4.1.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "0.1.0",
        "0.2.0",
        "0.3.0",
        "0.4.0",
        "0.4.1",
        "0.5.0",
        "0.6.0",
        "0.6.1",
        "0.7.0",
        "0.7.0b1",
        "0.7.1",
        "0.7.2",
        "0.8.0",
        "0.8.0b1",
        "0.8.0b2",
        "0.8.0b3",
        "0.8.0b4",
        "0.8.0b5",
        "0.8.0rc1",
        "0.8.0rc2",
        "0.8.1",
        "0.9.0",
        "0.9.0b1",
        "0.9.0b2",
        "0.9.0b3",
        "0.9.0rc1",
        "0.9.1",
        "0.9.2",
        "0.9.3",
        "0.9.4",
        "0.9.5",
        "0.9.6",
        "1.0.0",
        "1.0.0b1",
        "1.0.0b2",
        "1.1.0",
        "1.1.0b1",
        "1.2.0",
        "1.2.0b1",
        "1.2.1",
        "1.2.2",
        "1.3.0",
        "1.4.0",
        "1.4.1",
        "1.4.2",
        "1.5.0",
        "1.5.1",
        "2.0.0",
        "2.0.0b1",
        "2.0.0b2",
        "2.0.0b3",
        "2.0.0rc1",
        "2.0.0rc2",
        "2.0.0rc3",
        "2.0.0rc4",
        "2.0.0rc5",
        "2.0.1",
        "2.0.2",
        "2.1.0",
        "2.1.1",
        "2.2.0",
        "2.2.1",
        "2.2.2",
        "2.3.0",
        "2.3.1",
        "3.0.0",
        "3.0.0b1",
        "3.1.0",
        "3.1.1",
        "4.0.0",
        "4.0.0b1",
        "4.0.0b2",
        "4.0.1",
        "4.0.2"
      ]
    }
  ],
  "aliases": [
    "CVE-2024-28233",
    "GHSA-7r3h-4ph8-w38g"
  ],
  "details": "### Impact\n\nAffected configurations:\n\n- Single-origin JupyterHub deployments\n- JupyterHub deployments with user-controlled applications running on subdomains or peer subdomains of either the Hub or a single-user server.\n\nBy tricking a user into visiting a malicious subdomain, the attacker can achieve an XSS directly affecting the former\u0027s session. More precisely, in the context of JupyterHub, this XSS could achieve the following:\n\n- Full access to JupyterHub API and user\u0027s single-user server, e.g.\n  - Create and exfiltrate an API Token\n  - Exfiltrate all files hosted on the user\u0027s single-user server: notebooks, images, etc.\n  - Install malicious extensions. They can be used as a backdoor to silently regain access to victim\u0027s session anytime.\n\n### Patches\n\nTo prevent cookie-tossing:\n\n- Upgrade to JupyterHub 4.1 (both hub and user environment)\n- enable per-user domains via `c.JupyterHub.subdomain_host = \"https://mydomain.example.org\"`\n- set `c.JupyterHub.cookie_host_prefix_enabled = True` to enable domain-locked cookies\n\nor, if available (applies to earlier JupyterHub versions):\n\n- deploy jupyterhub on its own domain, not shared with any other services\n- enable per-user domains via `c.JupyterHub.subdomain_host = \"https://mydomain.example.org\"`",
  "id": "PYSEC-2026-1480",
  "modified": "2026-07-07T17:24:22.919266Z",
  "published": "2026-07-07T11:45:36.867733Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/jupyterhub/jupyterhub/security/advisories/GHSA-7r3h-4ph8-w38g"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2024-28233"
    },
    {
      "type": "FIX",
      "url": "https://github.com/jupyterhub/jupyterhub/commit/e2798a088f5ad45340fe79cdf1386198e664f77f"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/jupyterhub/jupyterhub"
    },
    {
      "type": "PACKAGE",
      "url": "https://pypi.org/project/jupyterhub"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/advisories/GHSA-7r3h-4ph8-w38g"
    }
  ],
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "Cross site scripting (XSS) in JupyterHub via Self-XSS leveraged by Cookie Tossing"
}



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  • Confirmed: The vulnerability has been validated from an analyst's perspective.
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  • 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.


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