CVE-2026-33709 JupyterHub has an Open Redirect Vulnerability

What is CVE-2026-33709?

CVE-2026-33709 is a medium-severity vulnerability in jupyterhub, published on 3 Apr 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

Official 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.

Weakness: CWE-601

Which versions are affected by CVE-2026-33709?

4 open source packages ship an affected version, including jupyterhub. It affects 1 product.

Products include Jupyter Jupyterhub.

How do I fix CVE-2026-33709?

Upgrade jupyterhub to 5.4.4 or later.

Is CVE-2026-33709 being exploited?

There is no known exploitation of CVE-2026-33709 in the wild and no public exploit code.

Other vulnerabilities in jupyterhub

• CVE-2024-28233 XSS in JupyterHub via Self-XSS leveraged by Cookie Tossing High 8.1
• CVE-2024-41942 JupyterHub has a privilege escalation vulnerability with the `admin:users` scope High 7.2
• CVE-2019-10255 Open Redirect vulnerability in jupyterhub and notebook Medium 6.1
• CVE-2026-40864 JupyterHub: Cross-origin form POSTs bypass XSRF Medium 5.4
• CVE-2020-36191 Cross-Site Request Forgery in JupyterHub Medium 4.5

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as BIT-jupyterhub-2026-33709, DEBIAN-CVE-2026-33709, GHSA-3vff-hjqv-m7h8, PYSEC-2026-2188, UBUNTU-CVE-2026-33709.