# CVE-2023-39968: Open Redirect Vulnerability in jupyter-server

> Attackers can redirect logged-in Jupyter users to malicious sites via crafted login links, bypassing URL restrictions.

- **Severity:** Medium 4.3 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** Yes
- **Published:** 28 Aug 2023
- **Updated:** 13 Feb 2025
- **Also known as:** DEBIAN-CVE-2023-39968, GHSA-r726-vmfq-j9j3, PYSEC-2023-155, UBUNTU-CVE-2023-39968

## What is CVE-2023-39968?

CVE-2023-39968 is a medium-severity vulnerability in jupyter-server jupyter_server, published on 28 Aug 2023. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

### Official description

jupyter-server is the backend for Jupyter web applications. Open Redirect Vulnerability. Maliciously crafted login links to known Jupyter Servers can cause successful login or an already logged-in session to be redirected to arbitrary sites, which should be restricted to Jupyter Server-served URLs. This issue has been addressed in commit `29036259` which is included in release 2.7.2. Users are advised to upgrade. There are no known workarounds for this vulnerability.

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

## Which versions are affected by CVE-2023-39968?

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 | 2.7.2 |
| `jupyter-server` | PyPI | All versions | 2.7.2 |
| `jupyter-server` | PyPI | All versions | 2.7.2 |

Products: Jupyter Jupyter Server.

## How do I fix CVE-2023-39968?

Upgrade jupyter-server to 2.7.2 or later.

## Is CVE-2023-39968 being exploited?

There is no known exploitation of CVE-2023-39968 in the wild and no public exploit code.

## Other vulnerabilities in jupyter-server 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-2023-39968 and fix it if it is affected.

What it is: CVE-2023-39968 is a medium-severity vulnerability in jupyter-server jupyter_server, published on 28 Aug 2023. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2023-39968 in the wild and no public exploit code.

Affected packages and fixed versions:
- jupyter-server (PyPI): affected all versions; fixed in 2.7.2
- jupyter-server (PyPI): affected all versions; fixed in 2.7.2
- jupyter-server (PyPI): affected all versions; fixed in 2.7.2

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-2023-39968/ (Markdown: https://insights.sbomify.com/CVE-2023-39968/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2023-39968
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2023-39968
- OSV: https://osv.dev/vulnerability/CVE-2023-39968

---
From sbomify Insights: https://insights.sbomify.com/CVE-2023-39968/
Summaries are generated and may contain mistakes; the official description above is the record.