---
id: CVE-2026-33709
aliases:
  - GHSA-3vff-hjqv-m7h8
  - BIT-jupyterhub-2026-33709
  - PYSEC-2026-2188
title: JupyterHub has an Open Redirect Vulnerability
summary: JupyterHub has an Open Redirect Vulnerability
severity: medium
cvss: 6.1
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N'
vendor: jupyterhub
product: jupyterhub
ecosystem: pip
affected:
  - jupyterhub < 5.4.4
patched:
  - jupyterhub 5.4.4
published: '2026-04-03'
updated: '2026-07-13'
source: OSV
sourceUrl: 'https://osv.dev/vulnerability/GHSA-3vff-hjqv-m7h8'
references:
  - url: >-
      https://github.com/jupyterhub/jupyterhub/security/advisories/GHSA-3vff-hjqv-m7h8
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-33709'
  - url: 'https://github.com/jupyterhub/jupyterhub'
  - url: 'https://github.com/jupyterhub/jupyterhub/releases/tag/5.4.4'
tags:
  - osv
  - pip
epss: 0.00206
epssPercentile: 0.11032
ingestedAt: '2026-07-13T18:57:52.106Z'
---

## Overview

## Affected Version

JupyterHub <= 5.4.3

## Impact

An open redirect vulnerability in JupyterHub <=5.4.3 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.

## Patches

Upgrade to JupyterHub 5.4.4

## Workarounds

A deployment can apply filters on the Location header in a reverse proxy such as nginx/apache/traefik.

## Affected packages

- `jupyterhub < 5.4.4`

## Remediation

Upgrade to a patched release:

- `jupyterhub 5.4.4`