CVE Vulnerabilities

CVE-2026-6657

Origin Validation Error

Published: Jun 03, 2026 | Modified: Jun 30, 2026
CVSS 3.x
8.8
HIGH
Source:
NVD
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
CVSS 2.x
RedHat/V2
RedHat/V3
6.1 MODERATE
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
Ubuntu
MEDIUM
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A vulnerability in jupyter-server versions 1.12.0 through 2.17.0 allows an attacker to bypass CORS origin validation when the allow_origin_pat configuration is used. The issue arises from the use of re.match() for validating the Origin header, which only anchors at the start of the string. This allows attacker-controlled domains such as trusted.example.com.evil.com to pass validation against patterns intended to match trusted.example.com. The vulnerability affects multiple locations in the codebase, including CORS headers, WebSocket connections, referer validation, and login redirects, potentially enabling phishing attacks, arbitrary code execution, and unauthorized access to sensitive API responses.

Weakness

The product does not properly verify that the source of data or communication is valid.

Affected Software

NameVendorStart VersionEnd Version
Jupyter_serverJupyter1.12.0 (including)2.17.0 (including)
Jupyter-serverUbuntuquesting*

References