---
id: CVE-2020-26275
aliases:
  - GHSA-9f66-54xg-pc2c
  - PYSEC-2020-346
  - PYSEC-2020-50
title: Jupyter Server open redirect vulnerability
summary: Jupyter Server 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: jupyter-server
product: jupyter-server
ecosystem: pip
affected:
  - jupyter-server < 1.1.1
patched:
  - jupyter-server 1.1.1
published: '2020-12-21'
updated: '2026-07-08'
source: OSV
sourceUrl: 'https://osv.dev/vulnerability/GHSA-9f66-54xg-pc2c'
references:
  - url: >-
      https://github.com/jupyter-server/jupyter_server/security/advisories/GHSA-9f66-54xg-pc2c
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2020-26275'
  - url: >-
      https://github.com/jupyter-server/jupyter_server/commit/85e4abccf6ea9321d29153f73b0bd72ccb3a6bca
  - url: 'https://advisory.checkmarx.net/advisory/CX-2020-4291'
  - url: 'https://github.com/jupyter-server/jupyter_server'
  - url: >-
      https://github.com/pypa/advisory-database/tree/main/vulns/jupyter-server/PYSEC-2020-346.yaml
  - url: >-
      https://github.com/pypa/advisory-database/tree/main/vulns/jupyter-server/PYSEC-2020-50.yaml
  - url: 'https://pypi.org/project/jupyter-server'
tags:
  - osv
  - pip
epss: 0.01379
epssPercentile: 0.70937
ingestedAt: '2026-07-08T18:25:47.839Z'
---

## Overview

### Impact
_What kind of vulnerability is it? Who is impacted?_

Open redirect vulnerability - a maliciously crafted link to a jupyter server could redirect the browser to a different website.

All jupyter servers running without a base_url prefix are technically affected, however, these maliciously crafted links can only be reasonably made for known jupyter server hosts. A link to your jupyter server may *appear* safe, but ultimately redirect to a spoofed server on the public internet. This same vulnerability was patched in upstream notebook v5.7.8.

### Patches

_Has the problem been patched? What versions should users upgrade to?_

Patched in jupyter_server 1.1.1. If upgrade is not available, a workaround can be to run your server on a url prefix:

```
jupyter server --ServerApp.base_url=/jupyter/
```

### References

[OWASP page on open redirects](https://cheatsheetseries.owasp.org/cheatsheets/Unvalidated_Redirects_and_Forwards_Cheat_Sheet.html)

### For more information

If you have any questions or comments about this advisory, or vulnerabilities to report, please email our security list [security@ipython.org](mailto:security@ipython.org).

Credit: Yaniv Nizry from CxSCA group at Checkmarx

## Affected packages

- `jupyter-server < 1.1.1`

## Remediation

Upgrade to a patched release:

- `jupyter-server 1.1.1`