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CVE-2026-40110

7.3 · HIGH

Jupyter Server is the backend for Jupyter web applications.

Published May 5, 2026CWE-777EPSS 0.47%

Overview

CVE-2026-40110 is a high-severity vulnerability. It was published on May 5, 2026 and has a CVSS 3.1 base score of 7.3 (HIGH).

This vulnerability has a CVSS 3.1 base score of 7.3, rated HIGH. It can be exploited remotely over the network. Some level of privileges is required for exploitation.

Technical 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.

Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

References

GitHubgithub.com/jupyter-server/jupyter_server/commit/057869a327c46730afede3eab0ca2d2e3e74aceaGitHubgithub.com/jupyter-server/jupyter_server/commit/49b34392feaa97735b3b777e3baf8f22f2a14ed8GitHubgithub.com/jupyter-server/jupyter_server/pull/603GitHubgithub.com/jupyter-server/jupyter_server/security/advisories/GHSA-24qx-w28j-9m6pRefaccess.redhat.com/errata/RHSA-2026:43038Refaccess.redhat.com/security/cve/CVE-2026-40110Refbugzilla.redhat.com/show_bug.cgi?id=2466912Refsecurity.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-40110.json

How CyberStrike helps

Frequently asked questions

What is CVE-2026-40110?

CVE-2026-40110 is a high-severity vulnerability. It was published on May 5, 2026 and has a CVSS 3.1 base score of 7.3 (HIGH).

How severe is CVE-2026-40110?

This vulnerability has a CVSS 3.1 base score of 7.3, rated HIGH. It can be exploited remotely over the network. Some level of privileges is required for exploitation.

How do I fix or remediate CVE-2026-40110?

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

How can CyberStrike help with CVE-2026-40110?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2026-40110 is actually reachable in your own applications and APIs, then verifies each finding before reporting it. That tells you if the weakness is a real, exploitable risk in your environment or a false positive you can safely deprioritize.

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