High 7.6Published May 5, 2026

CVE-2026-40110jupyter-server CORS origin validation bypass via unanchored regex in allow_origin_pat

Updated under an hour ago (Oct 27, 2026, 11:20 PM ET)

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No exploitation reported and no EPSS estimate yet.

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Every CVE for jupyter-server jupyter_server

Exploited in the last 30 days

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.

CVSS: 7.6 HIGH (v4.0, CNA)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
Weakness (CWE): CWE-777, CWE-625
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: GitHub_M
NVD analysis: Modified
Record last updated: Jul 22, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

jupyter-server jupyter_server jupyter_server:jupyter_server (from the name)	through 2.17.0	CNA record
Red Hat Red Hat Migration Toolkit for Applications 8.2 redhat:migration_toolkit_applications	from 1784109883 not affected	CISA ADP
Red Hat Red Hat OpenShift AI (RHOAI) redhat:openshift_ai	All versions	CISA ADP
jupyter jupyter_server jupyter:jupyter_server	before 2.18.0	NVD

References

References

https://github.com/jupyter-server/jupyter_server/security/advisories/GHSA-24qx-w28j-9m6p	x-refsource-confirm, mitigation, patch, vendor-advisory
https://github.com/jupyter-server/jupyter_server/pull/603	x-refsource-misc, issue-tracking
https://github.com/jupyter-server/jupyter_server/commit/057869a327c46730afede3eab0ca2d2e3e74acea	x-refsource-misc, patch
https://github.com/jupyter-server/jupyter_server/commit/49b34392feaa97735b3b777e3baf8f22f2a14ed8	x-refsource-misc, patch
https://access.redhat.com/errata/RHSA-2026:43038
https://access.redhat.com/security/cve/CVE-2026-40110
https://bugzilla.redhat.com/show_bug.cgi?id=2466912
https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-40110.json

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.