CVE-2026-40110
Severity CVSS v4.0:
HIGH
Type:
Unavailable / Other
Publication date:
05/05/2026
Last modified:
05/05/2026
Description
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.
Impact
Base Score 4.0
7.60
Severity 4.0
HIGH
References to Advisories, Solutions, and Tools
- https://github.com/jupyter-server/jupyter_server/commit/057869a327c46730afede3eab0ca2d2e3e74acea
- https://github.com/jupyter-server/jupyter_server/commit/49b34392feaa97735b3b777e3baf8f22f2a14ed8
- https://github.com/jupyter-server/jupyter_server/pull/603
- https://github.com/jupyter-server/jupyter_server/security/advisories/GHSA-24qx-w28j-9m6p