BREW-JUPYTERLAB-CVE-2026-40110 (GHSA-24QX-W28J-9M6P)

Vulnerability from osv_homebrew – Published: 2026-08-13 17:01 – Updated: 2026-09-25 10:03 – Source website
VLAI
Summary
Jupyter Server has a CORS Origin Validation Bypass via `re.match()` in `allow_origin_pat`
Details

Jupyter Server uses re.match() to validate the Origin header against the allow_origin_pat configuration.

Since re.match() only anchors at the start of the string, an attacker who controls a domain like http://trusted.example.com.evil.com/ passes validation against a pattern intended to match only trusted.example.com.

Impact

<=2.17.0

Patches

057869a327c46730afede3eab0ca2d2e3e74acea, 49b34392feaa97735b3b777e3baf8f22f2a14ed8

Workarounds

Wrap your allow_origin_pat value with ^ and $

References

https://github.com/jupyter-server/jupyter_server/pull/603 https://docs.python.org/3/library/re.html#re.fullmatch https://docs.python.org/3/library/re.html#re.match

Severity
7.6 (High)
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:H/VI:H/VA:L/SC:L/SI:L/SA:L
References
To clipboard 

{
  "affected": [
    {
      "ecosystem_specific": {
        "fix": "bump",
        "range_state": "fixed",
        "resource": "jupyter-server",
        "resource_purl": "pkg:pypi/jupyter-server@2.21.1",
        "upstream_fixed_in": "2.18.0"
      },
      "package": {
        "ecosystem": "Homebrew",
        "name": "jupyterlab",
        "purl": "pkg:brew/jupyterlab"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "3.0.0"
            },
            {
              "fixed": "4.5.7_1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "database_specific": {
    "confidence": "high",
    "source": "matched",
    "strategy": "registry",
    "upstream_evidence": [
      {
        "ecosystem": "PyPI",
        "key": "pkg:pypi/jupyter-server@2.21.1",
        "name": "jupyter-server",
        "resource": "jupyter-server",
        "strategy": "registry",
        "subject_version": "2.21.1"
      }
    ]
  },
  "details": "Jupyter Server uses `re.match()` to validate the Origin header against the `allow_origin_pat` configuration.\n\nSince `re.match()` only anchors at the start of the string, an attacker who controls a domain like `http://trusted.example.com.evil.com/` passes validation against a pattern intended to match only `trusted.example.com`.\n\n### Impact\n\n\u003c=2.17.0\n\n### Patches\n\n057869a327c46730afede3eab0ca2d2e3e74acea, 49b34392feaa97735b3b777e3baf8f22f2a14ed8 \n\n### Workarounds\n\nWrap your `allow_origin_pat` value with `^` and `$`\n\n### References\n\nhttps://github.com/jupyter-server/jupyter_server/pull/603\nhttps://docs.python.org/3/library/re.html#re.fullmatch\nhttps://docs.python.org/3/library/re.html#re.match",
  "id": "BREW-jupyterlab-CVE-2026-40110",
  "modified": "2026-09-25T10:03:02Z",
  "published": "2026-08-13T17:01:18Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/jupyter-server/jupyter_server/security/advisories/GHSA-24qx-w28j-9m6p"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-40110"
    },
    {
      "type": "WEB",
      "url": "https://github.com/jupyter-server/jupyter_server/pull/603"
    },
    {
      "type": "WEB",
      "url": "https://github.com/jupyter-server/jupyter_server/commit/057869a327c46730afede3eab0ca2d2e3e74acea"
    },
    {
      "type": "WEB",
      "url": "https://github.com/jupyter-server/jupyter_server/commit/49b34392feaa97735b3b777e3baf8f22f2a14ed8"
    },
    {
      "type": "WEB",
      "url": "https://access.redhat.com/errata/RHSA-2026:43038"
    },
    {
      "type": "WEB",
      "url": "https://access.redhat.com/security/cve/CVE-2026-40110"
    },
    {
      "type": "WEB",
      "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2466912"
    },
    {
      "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-2026-2187.yaml"
    },
    {
      "type": "WEB",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-40110.json"
    }
  ],
  "schema_version": "1.7.3",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:H/VI:H/VA:L/SC:L/SI:L/SA:L",
      "type": "CVSS_V4"
    }
  ],
  "summary": "Jupyter Server has a  CORS Origin Validation Bypass via `re.match()` in `allow_origin_pat`",
  "upstream": [
    "GHSA-24qx-w28j-9m6p",
    "CVE-2026-40110",
    "PYSEC-2026-2187"
  ]
}



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