GHSA-5MRQ-X3X5-8V8F

Vulnerability from github – Published: 2026-05-05 17:03 – Updated: 2026-05-05 17:03
VLAI?
Summary
Jupyter Server's Authentication Cookies Remain Valid After Password Reset and Server Restart
Details

Summary

A persistent cookie secret vulnerability allows authenticated users to maintain indefinite access even after password changes.

The cookie secret used to sign authentication cookies is stored in a permanent file (~/.local/share/jupyter/runtime/jupyter_cookie_secret) that is never automatically rotated or cleared, allowing stolen or compromised cookies to remain valid indefinitely regardless of password resets.

PoC

  • Start a Jupyter server with password authentication: jupyter server password, jupyter server
  • Log in with the password and capture the authentication cookie (e.g., just login with a browser).
  • Change the password to revoke access: jupyter server password
  • Restart the server
  • Use the old stolen cookie => remains valid and provides full authenticated access.

Impact

  • All jupyter-server deployments using password authentication where security incidents may occur
  • Multi-user systems where one user's compromised session should be revocable by administrators
  • Shared or public-facing Jupyter servers where credential rotation is a security requirement
  • Any deployment where password changes are expected to revoke existing sessions

Patches

Jupyter Server 2.18+

Workaround

rm ~/.local/share/jupyter/runtime/jupyter_cookie_secret
# Then restart the server
Severity ?
6.8 (Medium)
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:N
Show details on source website
To clipboard 

{
  "affected": [
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 2.17.0"
      },
      "package": {
        "ecosystem": "PyPI",
        "name": "jupyter-server"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "2.18.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-40934"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-613"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-05-05T17:03:24Z",
    "nvd_published_at": null,
    "severity": "MODERATE"
  },
  "details": "## Summary\n\nA persistent cookie secret vulnerability allows authenticated users to maintain indefinite access even after password changes. \n\nThe cookie secret used to sign authentication cookies is stored in a permanent file (`~/.local/share/jupyter/runtime/jupyter_cookie_secret`) that is never automatically rotated or cleared, allowing stolen or compromised cookies to remain valid indefinitely regardless of password resets.\n\n## PoC\n\n- Start a Jupyter server with password authentication: `jupyter server password`, `jupyter server`\n- Log in with the password and capture the authentication cookie (e.g., just login with a browser).\n- Change the password to revoke access: `jupyter server password`\n- Restart the server\n- Use the old stolen cookie =\u003e remains valid and provides full authenticated access.\n\n## Impact\n\n- All jupyter-server deployments using password authentication where security incidents may occur\n- Multi-user systems where one user\u0027s compromised session should be revocable by administrators\n- Shared or public-facing Jupyter servers where credential rotation is a security requirement\n- Any deployment where password changes are expected to revoke existing sessions\n\n## Patches\n\nJupyter Server 2.18+\n\n## Workaround\n\n```bash\nrm ~/.local/share/jupyter/runtime/jupyter_cookie_secret\n# Then restart the server\n```",
  "id": "GHSA-5mrq-x3x5-8v8f",
  "modified": "2026-05-05T17:03:24Z",
  "published": "2026-05-05T17:03:24Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/jupyter-server/jupyter_server/security/advisories/GHSA-5mrq-x3x5-8v8f"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/jupyter-server/jupyter_server"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "Jupyter Server\u0027s Authentication Cookies Remain Valid After Password Reset and Server Restart"
}


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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

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.