How severe is CVE-2026-33709?

CVE-2026-33709 has a CVSS 3.x base score of 6.1, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is low, integrity low, and availability none.

Is CVE-2026-33709 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (13th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-33709?

CVE-2026-33709 affects Jupyter Jupyterhub. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-33709?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

Does CVE-2026-33709 have an EU (EUVD) identifier?

Yes. CVE-2026-33709 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-18880.

When was CVE-2026-33709 published?

CVE-2026-33709 was published on 2026-04-03 and last updated on 2026-06-17.

CVE-2026-33709

CVE-2026-33709 is a medium-severity vulnerability in Jupyter Jupyterhub with a CVSS 3.x base score of 6.1. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-601.

Key facts

Severity: Medium (CVSS 3.x base score 6.1)
CVSS v4: 5.1
EPSS exploit prediction: 0% (13th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-18880
Weakness: CWE-601
Affected product: Jupyter Jupyterhub
Published: 2026-04-03
Last modified: 2026-06-17

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.

Frequently asked questions

What is CVE-2026-33709?: 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.
How severe is CVE-2026-33709?: CVE-2026-33709 has a CVSS 3.x base score of 6.1, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is low, integrity low, and availability none.
Is CVE-2026-33709 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (13th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-33709?: CVE-2026-33709 affects Jupyter Jupyterhub. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-33709?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2026-33709 have an EU (EUVD) identifier?: Yes. CVE-2026-33709 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-18880.
When was CVE-2026-33709 published?: CVE-2026-33709 was published on 2026-04-03 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:jupyter:jupyterhub:*:*:*:*:*:*:*:*

More vulnerabilities in Jupyter Jupyterhub

CVE-2024-28233 — High (CVSS 8.1): JupyterHub is an open source multi-user server for Jupyter notebooks. By tricking a user into visiting a malicious…
CVE-2024-41942 — High (CVSS 7.2): JupyterHub is software that allows one to create a multi-user server for Jupyter notebooks. Prior to versions 4.1.6 and…
CVE-2019-10255 — Medium (CVSS 6.1): An Open Redirect vulnerability for all browsers in Jupyter Notebook before 5.7.7 and some browsers (Chrome, Firefox) in…
CVE-2026-40864 — Medium (CVSS 5.4): JupyterHub is software that allows users to create a multi-user server for Jupyter notebooks. In versions 4.1.0 through…
CVE-2020-36191 — Medium (CVSS 4.5): JupyterHub 1.1.0 allows CSRF in the admin panel via a request that lacks an _xsrf field, as demonstrated by a…
CVE-2021-41247 — Low (CVSS 3.5): JupyterHub is an open source multi-user server for Jupyter notebooks. In affected versions users who have multiple…

All CVEs affecting Jupyter Jupyterhub →

Other CWE-601 (Open Redirect) vulnerabilities

CVE-2018-3774 — Critical (CVSS 10.0): Incorrect parsing in url-parse <1.4.3 returns wrong hostname which leads to multiple vulnerabilities such as SSRF, Open…
CVE-2019-25282 — Critical (CVSS 9.8): V-SOL GPON/EPON OLT Platform v2.03 contains an open redirect vulnerability in the script that allows attackers to…
CVE-2020-36912 — Critical (CVSS 9.8): Plexus anblick Digital Signage Management 3.1.13 contains an open redirect vulnerability in the 'PantallaLogin' script…
CVE-2025-43526 — Critical (CVSS 9.8): This issue was addressed with improved URL validation. This issue is fixed in Safari 26.2, macOS Tahoe 26.2. On a Mac…
CVE-2025-55031 — Critical (CVSS 9.8): Malicious pages could use Firefox for iOS to pass FIDO: links to the OS and trigger the hybrid passkey transport. An…
CVE-2024-22891 — Critical (CVSS 9.8): Nteract v.0.28.0 was discovered to contain a remote code execution (RCE) vulnerability via the Markdown link.

Browse all CWE-601 (Open Redirect) vulnerabilities →

Threat intelligence

Threat-intel indicators referencing this CVE:

146.190.112.200 (ipv4-addr)