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CVE-2026-40110

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

Published: May 5, 2026Updated: Jul 24, 2026 Sources: CVE List NVDCWE-777
7.3HIGH
NVD MITRE
EPSS Score
0.3%
Top 73.3%
CISA KEV
Not in KEV
Exploits
No Known Exploits
Remediation
Patch Available
Self-Check
OpenVAS

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.

No summary for this CVE yet.

CVSS Vector Breakdown

AV:NAC:LPR:LUI:RS:UC:HI:HA:N
Exploitability
AV:NAttack Vector
Network
AC:LAttack Complexity
Low
PR:LPrivileges Required
Low
UI:RUser Interaction
Required
Scope
S:UScope
Unchanged
Impact
C:HConfidentiality
High
I:HIntegrity
High
A:NAvailability
None
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Weaknesses

CWE-777CWE-625

Affected Products

jupyter-server
oss-project·USaka jupyter-scheduler, jupyter_server
jupyter_serverOn-prem
AI / ML / notebook-mlops
jupyter
oss-projectaka notebook, jupyter server, jupyterlab
jupyter serverOn-premWeb App
AI / ML / notebook-mlops

Exploitability

Official Patch Available
Workaround Available
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References

https://github.com/jupyter-server/jupyter_server/security/advisories/GHSA-24qx-w28j-9m6p
github.com
https://github.com/jupyter-server/jupyter_server/pull/603
github.com
https://github.com/jupyter-server/jupyter_server/commit/057869a327c46730afede3eab0ca2d2e3e74acea
github.com
and 5 more references View all →

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