Is CVE-2026-40110 in the CISA KEV catalog?

No. CVE-2026-40110 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2026-40110?

CVE-2026-40110 has a CVSS v3 base score of 7.3 (HIGH).

What is the EPSS score for CVE-2026-40110?

CVE-2026-40110 has an EPSS score of 0.33% (26th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix CVE-2026-40110?

Upgrade jupyter-server on debian unstable to 2.20.0-1 or later.

CVE & CISA-KEV Catalog

CVE-2026-40110

HIGH

7.3

CVSS v3

NVD

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.

CWE-777 CWE-625

How to fix

Remediation Available

jupyter-serverDebian

Fixed in:2.20.0-1CVE-2026-40110

TridentStack Control can deploy fixes like this automatically across your Windows, macOS, and Linux fleet. See how it works

Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v3 Vector

Exploitability

Attack VectorNetwork

Attack ComplexityLow

Privileges RequiredLow

User InteractionRequired

ScopeUnchanged

Impact

ConfidentialityHigh

IntegrityHigh

AvailabilityNone

CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:N

Exploit Intelligence

0.33%probability of exploitation in 30 days

26thpercentile

Low risk: more likely to be exploited than 26% of all known CVEs.

References

Patch3

Issue Tracking1

github.com

Other references3

Related Vulnerabilities

Other CWE-777 vulnerabilities, ordered by exploit likelihood. View all

CVE	Severity	CVSS	EPSS	Exploited	Fix
CVE-2026-56021	Medium	5.3	0.3%	-	-
CVE-2026-39087	Medium	6.4	0.3%	-	-

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-07-15.