id: PYSEC-2026-2187
published: "2026-05-05T22:16:00.663Z"
modified: "2026-07-13T05:49:16.941897Z"
aliases:
- CVE-2026-40110
- GHSA-24qx-w28j-9m6p
details: Jupyter Server is the backend for Jupyter web applications. In versions 2.17.0 and earlier, the Origin header validation uses Python's re.match() to check incoming origins against the allow_origin_pat configuration value. Because re.match() only anchors at the start of the string and does not require a full match, a pattern intended to match only a trusted domain (e.g., trusted.example.com) will also match any origin that begins with that domain followed by additional characters (e.g., trusted.example.com.evil.com). An attacker who controls such a domain can bypass the CORS origin restriction and make cross-origin requests to the Jupyter Server API from an untrusted site. This issue has been fixed in version 2.18.0.
affected:
- package:
    name: jupyter-server
    ecosystem: PyPI
    purl: pkg:pypi/jupyter-server
  ranges:
  - type: ECOSYSTEM
    events:
    - introduced: "0"
    - fixed: 2.18.0
  versions:
  - 0.0.0
  - 0.0.1
  - 0.0.2
  - 0.0.3
  - 0.0.4
  - 0.0.5
  - 0.1.0
  - 0.1.1
  - 0.2.0
  - 0.2.1
  - 0.3.0
  - 1.0.0
  - 1.0.0rc0
  - 1.0.0rc1
  - 1.0.0rc10
  - 1.0.0rc11
  - 1.0.0rc12
  - 1.0.0rc13
  - 1.0.0rc14
  - 1.0.0rc15
  - 1.0.0rc16
  - 1.0.0rc2
  - 1.0.0rc3
  - 1.0.0rc4
  - 1.0.0rc5
  - 1.0.0rc6
  - 1.0.0rc7
  - 1.0.0rc8
  - 1.0.0rc9
  - 1.0.1
  - 1.0.10
  - 1.0.11
  - 1.0.2
  - 1.0.3
  - 1.0.4
  - 1.0.5
  - 1.0.6
  - 1.0.7
  - 1.0.8
  - 1.0.9
  - 1.1.0
  - 1.1.1
  - 1.1.2
  - 1.1.3
  - 1.1.4
  - 1.10.0
  - 1.10.1
  - 1.10.2
  - 1.11.0
  - 1.11.1
  - 1.11.2
  - 1.12.0
  - 1.12.1
  - 1.13.0
  - 1.13.1
  - 1.13.2
  - 1.13.3
  - 1.13.4
  - 1.13.5
  - 1.15.0
  - 1.15.1
  - 1.15.2
  - 1.15.3
  - 1.15.4
  - 1.15.5
  - 1.15.6
  - 1.16.0
  - 1.17.0
  - 1.17.1
  - 1.18.0
  - 1.18.1
  - 1.19.0
  - 1.19.1
  - 1.2.0
  - 1.2.1
  - 1.2.2
  - 1.2.3
  - 1.21.0
  - 1.23.0
  - 1.23.1
  - 1.23.2
  - 1.23.3
  - 1.23.4
  - 1.23.5
  - 1.23.6
  - 1.24.0
  - 1.3.0
  - 1.4.0
  - 1.4.1
  - 1.5.0
  - 1.5.1
  - 1.6.0
  - 1.6.1
  - 1.6.2
  - 1.6.3
  - 1.6.4
  - 1.7.0
  - 1.7.0a1
  - 1.7.0a2
  - 1.8.0
  - 1.9.0
  - 2.0.0
  - 2.0.0a0
  - 2.0.0a1
  - 2.0.0a2
  - 2.0.0b0
  - 2.0.0b1
  - 2.0.0rc0
  - 2.0.0rc1
  - 2.0.0rc2
  - 2.0.0rc3
  - 2.0.0rc4
  - 2.0.0rc5
  - 2.0.0rc6
  - 2.0.0rc7
  - 2.0.0rc8
  - 2.0.1
  - 2.0.2
  - 2.0.3
  - 2.0.4
  - 2.0.5
  - 2.0.6
  - 2.0.7
  - 2.1.0
  - 2.10.0
  - 2.10.1
  - 2.11.0
  - 2.11.1
  - 2.11.2
  - 2.12.0
  - 2.12.1
  - 2.12.2
  - 2.12.3
  - 2.12.4
  - 2.12.5
  - 2.13.0
  - 2.14.0
  - 2.14.1
  - 2.14.2
  - 2.15.0
  - 2.16.0
  - 2.17.0
  - 2.2.0
  - 2.2.1
  - 2.3.0
  - 2.4.0
  - 2.5.0
  - 2.6.0
  - 2.7.0
  - 2.7.1
  - 2.7.2
  - 2.7.3
  - 2.8.0
  - 2.9.0
  - 2.9.1
  ecosystem_specific: {}
references:
- type: WEB
  url: https://access.redhat.com/security/cve/CVE-2026-40110
- type: WEB
  url: https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-40110.json
- type: REPORT
  url: https://bugzilla.redhat.com/show_bug.cgi?id=2466912
- type: REPORT
  url: https://github.com/jupyter-server/jupyter_server/pull/603
- type: FIX
  url: https://github.com/jupyter-server/jupyter_server/commit/057869a327c46730afede3eab0ca2d2e3e74acea
- type: FIX
  url: https://github.com/jupyter-server/jupyter_server/commit/49b34392feaa97735b3b777e3baf8f22f2a14ed8
- type: FIX
  url: https://github.com/jupyter-server/jupyter_server/security/advisories/GHSA-24qx-w28j-9m6p
severity:
- type: CVSS_V3
  score: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:N