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© 2026 FAUCET Technologies LLC. All rights reserved.

CVE-2026-40110

32
FAUCET Score

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.

First published: May 5, 2026Last modified: May 7, 2026

Impacted Technologies

VendorProductVersion(s)CPE
< 2.18.0CPE matchmatch criteria
cpe:2.3:a:jupyter:jupyter_server:*:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 4.0

7.6HIGH

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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Attack Vector
NETWORK
Attack Complexity
LOW
Attack Requirements
PRESENT
Privileges Required
NONE
User Interaction
PASSIVE
VS Confidentiality
HIGH
VS Integrity
HIGH
VS Availability
LOW
SS Confidentiality
LOW
SS Integrity
LOW
SS Availability
LOW
Exploit Maturity
NOT_DEFINED
CvssVersion
4.0

Exploit Intelligence

EPSS Score
0.34%
Probability of exploitation in next 30 days
EPSS Percentile
26.6%
Percentile rank of EPSS score among Peer Group
As of 2026-07-26
Model: v2026.06.15
This CVE's current EPSS score of 0.0034 is in the 34th percentile among its peer group of 890 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.3 Bluesky, 0.1 Mastodon, and 0.1 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.1 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (2)

github_advisorypatch availablevia nvd_reference
View patch
pippatch availablevia ghsa
Product: jupyter-serverFixed in: 2.18.0

Vendor Advisories (1)

pipGHSA-24qx-w28j-9m6phigh

Jupyter Server has a CORS Origin Validation Bypass via `re.match()` in `allow_origin_pat` (from huntr)

May 5, 2026

References

access.redhat.com / errata/RHSA-2026:43038
access.redhat.com / security/cve/CVE-2026-40110
bugzilla.redhat.com / show_bug.cgi
security.access.redhat.com / data/csaf/v2/vex/2026/cve-2026-40110.json
github.com / jupyter-server/jupyter_server/commit/057869a327c46730afede3eab0ca2d2e3e74acea
Patch
github.com / jupyter-server/jupyter_server/commit/49b34392feaa97735b3b777e3baf8f22f2a14ed8
Patch
github.com / jupyter-server/jupyter_server/pull/603
Issue Tracking
github.com / jupyter-server/jupyter_server/security/advisories/GHSA-24qx-w28j-9m6p
MitigationPatchVendor Advisory