CVE-2026-33709
MediumCVSS 6.1Exploitation Probability (EPSS)
Low risk13th percentile - higher than 13% of all known CVEs
Summary
JupyterHub before version 5.4.4 has an open redirect vulnerability that 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, bypassing JupyterHub's check to prevent this.
Risk Assessment
An attacker can use this for phishing, redirecting users after login to a malicious site, potentially leading to theft of login credentials or other sensitive information.
Recommendation
Update JupyterHub to version 5.4.4, which contains the fix.
Other vulnerabilities in JupyterHub
See all- CVE-2026-54338Medium
JupyterHub before version 5.5.0 has a vulnerability where invalid input to form-based login authenticators can place an unbounded attacker-controlled username in failed-login logs, allowing an unauthenticated attacker to consume logging and storage resources.
- CVE-2026-40864Medium
JupyterHub versions 4.1.0 through 5.4.4 inappropriately treated requests with Sec-Fetch-Mode: no-cors as same-origin requests, bypassing XSRF checks. This affects only HTTP form endpoints, allowing attackers to trigger server spawn and, if the attacker is a JupyterHub user with share permissions, force a user to accept a share and gain access to the attacker's server.
Original NVD description (English source)
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.
Vulnerability data from NVD (NIST) · CISA KEV · EPSS