CVE-2026-33709
Received Received - Intake
Open Redirect Vulnerability in JupyterHub Allows Phishing Redirects

Publication date: 2026-04-03

Last updated on: 2026-04-22

Assigner: GitHub, Inc.

Description
JupyterHub is software that allows one to create a multi-user server for Jupyter notebooks. Prior to version 5.4.4, an open redirect vulnerability in JupyterHub allows attackers to construct links which, when clicked, take users to the JupyterHub login page, after which they are sent to an arbitrary attacker-controlled site outside JupyterHub instead of a JupyterHub page, bypassing JupyterHub's check to prevent this. This issue has been patched in version 5.4.4.
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Meta Information
Published
2026-04-03
Last Modified
2026-04-22
Generated
2026-06-16
AI Q&A
2026-04-04
EPSS Evaluated
2026-06-15
NVD
CVE-2026-33709
Affected Vendors & Products
Showing 1 associated CPE
Vendor Product Version / Range
jupyter jupyterhub to 5.4.4 (exc)
Helpful Resources
Exploitability
CWE
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KEV
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CWE ID Description
CWE-601 The web application accepts a user-controlled input that specifies a link to an external site, and uses that link in a redirect.
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Impact Analysis

The vulnerability can be exploited by attackers to redirect users to malicious websites after they attempt to log in to JupyterHub. This could lead to phishing attacks, where users are tricked into providing sensitive information or downloading malicious content, potentially compromising user security and trust.

Executive Summary

This vulnerability is an open redirect issue in JupyterHub versions prior to 5.4.4. It allows attackers to create specially crafted links that, when clicked, first take users to the JupyterHub login page and then redirect them to an arbitrary attacker-controlled website outside of JupyterHub. This bypasses JupyterHub's normal checks designed to prevent such redirects.

Mitigation Strategies

To mitigate this vulnerability, you should upgrade JupyterHub to version 5.4.4 or later, where the open redirect issue has been patched.

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