CVE-2026-40110

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 v3 7.3 HIGH

7.3^/10

CVSS v3 : HIGH

Vector :

Exploitability : 2.1 / Impact : 5.2

Attack Vector NETWORK

Attack Complexity LOW

Privileges Required LOW

User Interaction REQUIRED

Confidentiality Impact HIGH

Integrity Impact HIGH

Availability Impact NONE

Scope UNCHANGED

References

Link	Resource
https://github.com/jupyter-server/jupyter_server/commit/057869a327c46730afede3eab0ca2d2e3e74acea	Patch
https://github.com/jupyter-server/jupyter_server/commit/49b34392feaa97735b3b777e3baf8f22f2a14ed8	Patch
https://github.com/jupyter-server/jupyter_server/pull/603	Issue Tracking
https://github.com/jupyter-server/jupyter_server/security/advisories/GHSA-24qx-w28j-9m6p	Mitigation Patch Vendor Advisory
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

Configurations

Configuration 1 (hide)

cpe:2.3:a:jupyter:jupyter_server:*:*:*:*:*:*:*:*

History

No history.

Information

Published : 2026-05-05 22:16

Updated : 2026-07-24 21:10

NVD link : CVE-2026-40110

Mitre link : CVE-2026-40110

CVE.ORG link : CVE-2026-40110

JSON object : View

Products Affected

jupyter

jupyter_server

CWE

CWE-777

Regular Expression without Anchors

CWE-625

Permissive Regular Expression

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"descriptions": [{"lang": "en", "value": "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."}, {"lang": "es", "value": "Jupyter Server es el backend para aplicaciones web de Jupyter. En las versiones 2.17.0 y anteriores, la validaci\u00f3n del encabezado Origin utiliza re.match() de Python para verificar los or\u00edgenes entrantes contra el valor de configuraci\u00f3n allow_origin_pat. Debido a que re.match() solo se ancla al inicio de la cadena y no requiere una coincidencia completa, un patr\u00f3n destinado a coincidir solo con un dominio de confianza (por ejemplo, trusted.example.com) tambi\u00e9n coincidir\u00e1 con cualquier origen que comience con ese dominio seguido de caracteres adicionales (por ejemplo, trusted.example.com.evil.com). Un atacante que controla dicho dominio puede eludir la restricci\u00f3n de origen CORS y realizar solicitudes de origen cruzado a la API de Jupyter Server desde un sitio no confiable. Este problema ha sido solucionado en la versi\u00f3n 2.18.0."}], "lastModified": "2026-07-24T21:10:00.143", "configurations": [{"nodes": [{"negate": false, "cpeMatch": [{"criteria": "cpe:2.3:a:jupyter:jupyter_server:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "E0B6C703-7E28-4F23-9878-E157975C32A4", "versionEndExcluding": "2.18.0"}], "operator": "OR"}]}], "sourceIdentifier": "security-advisories@github.com"}