CVE-2026-6657

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.

CVSS v3 8.8 HIGH

8.8^/10

CVSS v3 : HIGH

Vector :

Exploitability : 2.8 / Impact : 5.9

Attack Vector NETWORK

Attack Complexity LOW

Privileges Required NONE

User Interaction REQUIRED

Confidentiality Impact HIGH

Integrity Impact HIGH

Availability Impact HIGH

Scope UNCHANGED

References

Link	Resource
https://huntr.com/bounties/18f642db-3569-43b3-b58d-ff97be4b09d7	Exploit Third Party Advisory
https://huntr.com/bounties/18f642db-3569-43b3-b58d-ff97be4b09d7	Exploit Third Party Advisory

Configurations

Configuration 1 (hide)

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

History

No history.

Information

Published : 2026-06-03 16:16

Updated : 2026-07-21 19:10

NVD link : CVE-2026-6657

Mitre link : CVE-2026-6657

CVE.ORG link : CVE-2026-6657

JSON object : View

Products Affected

jupyter

jupyter_server

CWE

CWE-346

Origin Validation Error

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