# CVE-2020-26232: Open redirect in Jupyter Server

> Attackers can craft links that redirect users from a trusted Jupyter Server to malicious external sites, potentially facilitating phishing attacks.

- **Severity:** Medium 4.1 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:N/I:L/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** Yes
- **Published:** 24 Nov 2020
- **Updated:** 4 Aug 2024
- **Also known as:** DEBIAN-CVE-2020-26232, GHSA-grfj-wjv9-4f9v, PYSEC-2020-234, openSUSE-SU-2024:11233-1, openSUSE-SU-2024:14143-1

## What is CVE-2020-26232?

CVE-2020-26232 is a medium-severity vulnerability in jupyter_server, published on 24 Nov 2020. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.

### Official description

Jupyter Server before version 1.0.6 has an Open redirect vulnerability. A maliciously crafted link to a jupyter server could redirect the browser to a different website. All jupyter servers 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.

Weakness: CWE-601 (URL Redirection to Untrusted Site)

## Which versions are affected by CVE-2020-26232?

3 open source packages ship an affected version, including jupyter-server. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `jupyter-server` | PyPI | All versions | 1.0.6 |
| `jupyter-server` | PyPI | All versions | 1.0.6 |
| `jupyter-server` | PyPI | All versions | 1.0.6 |

Products: Jupyter Jupyter Server.

## How do I fix CVE-2020-26232?

Upgrade jupyter-server to 1.0.6 or later.

## Is CVE-2020-26232 being exploited?

There is no known exploitation of CVE-2020-26232 in the wild and no public exploit code.

## Other vulnerabilities in jupyter_server

- [CVE-2026-44727](https://insights.sbomify.com/CVE-2026-44727/): Jupyter Server: Stored XSS in `NbconvertFileHandler` / `NbconvertPostHandler` via missing `sandbox` CSP (critical 9.3)
- [CVE-2026-35397](https://insights.sbomify.com/CVE-2026-35397/): jupyter-server path traversal allows access to sibling directories sharing root_dir name prefix (high 7.6)
- [CVE-2026-40110](https://insights.sbomify.com/CVE-2026-40110/): jupyter-server CORS origin validation bypass via unanchored regex in allow_origin_pat (high 7.6)
- [CVE-2026-40934](https://insights.sbomify.com/CVE-2026-40934/): jupyter-server authentication cookies remain valid after password reset due to static cookie secret (high 7.6)
- [CVE-2024-35178](https://insights.sbomify.com/CVE-2024-35178/): Jupyter server on Windows discloses Windows user password hash (high 7.5)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2020-26232 and fix it if it is affected.

What it is: CVE-2020-26232 is a medium-severity vulnerability in jupyter_server, published on 24 Nov 2020. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2020-26232 in the wild and no public exploit code.

Affected packages and fixed versions:
- jupyter-server (PyPI): affected all versions; fixed in 1.0.6
- jupyter-server (PyPI): affected all versions; fixed in 1.0.6
- jupyter-server (PyPI): affected all versions; fixed in 1.0.6

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2020-26232/ (Markdown: https://insights.sbomify.com/CVE-2020-26232/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2020-26232
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-26232
- OSV: https://osv.dev/vulnerability/CVE-2020-26232

---
From sbomify Insights: https://insights.sbomify.com/CVE-2020-26232/
Summaries are generated and may contain mistakes; the official description above is the record.