GHSA-5MRQ-X3X5-8V8F

Vulnerability from github – Published: 2026-05-05 17:03 – Updated: 2026-06-06 00:27
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
7.6 (High)
CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA: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": "2026-05-05T22:16:00Z",
    "severity": "HIGH"
  },
  "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": "2026-06-06T00:27:08Z",
  "published": "2026-05-05T17:03:24Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/jupyter-server/jupyter_server/security/advisories/GHSA-5mrq-x3x5-8v8f"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-40934"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/jupyter-server/jupyter_server"
    },
    {
      "type": "WEB",
      "url": "https://github.com/pypa/advisory-database/tree/main/vulns/jupyter-server/PYSEC-2026-69.yaml"
    }
  ],
  "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"
    },
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "Jupyter Server\u0027s Authentication Cookies Remain Valid After Password Reset and Server Restart"
}



Log in or create an account to share your comment.




Tags
Taxonomy of the tags.




Drag nodes to arrange them. Double-click a related vulnerability to open it, or a source to visit its link. The Physics button on the left tunes the layout and the simulation; the legend at the bottom left hides or shows nodes by kind and by sighting type.

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.
Vulnerability timeline

Sightings and recorded dates, grouped by day · UTC

JSON
How durations are calculated

Following the VTEM framework (Black Hat USA 2015), time to patch starts when the vendor or a coordinator was informed, total time to patch at discovery, and disclosure to patch at public disclosure; vendor response time runs from the report to its acknowledgement. Time to exploit and time unpatched start at the earliest discovery or report, falling back to public disclosure. Unpatched time ends at the first recorded patch, or the calculation time when no patch is recorded. Exploitation to patch shows the interval between those two events; a published proof of concept is a public exploit, not exploitation.

Each result shows its source dates. A negative interval means the end event came first; when date-only inputs leave the order open, the result says so. Date-only inputs are approximate. The earliest evidence wins: KEV report dates and sightings are labelled as such. Records describing another vulnerability are listed but never calculated from, and a PoC alone does not establish exploitation. Missing patch evidence does not prove that no patch exists. Filters below change the event list only.

Loading timeline…




    Related by attack behaviour

    Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.