CORS Origin Validation Bypass in jupyter-server_CVE-2026-6657

6.1 / 10

MEDIUM

CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

Description

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.

Basic Information

ID CVE-2026-6657

Source @huntr_ai

Published Jun 3, 2026 at 15:06

Affected Product

Vendor jupyter

Product jupyter/jupyter

Version unspecified

Affected Versions jupyter jupyter/jupyter unspecified

CWE Classification

CWE-346

References

huntr.com /bounties/18f642db-3569-43b3-b58d-ff97be4b09d7

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    "published": "2026-06-03T15:06:56.598Z",
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