CVE-2026-5422 Path Traversal in jupyter/jupyter
Attackers can bypass directory restrictions to read or modify files in sibling directories, exposing sensitive data in shared environments.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-5422?
CVE-2026-5422 is a medium-severity path traversal vulnerability in jupyter/jupyter, published on 2 Jun 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Official description
A path traversal vulnerability exists in jupyter-server version 2.17.0 due to an incorrect root directory boundary check in the _get_os_path() function within jupyter_server/services/contents/fileio.py. The check uses startswith(root) without appending a trailing path separator, allowing sibling directories with names starting with the same prefix as root_dir to bypass the check. Additionally, the to_os_path() function in utils.py does not strip ".." from path parts, enabling traversal sequences to bypass the vulnerable check. This vulnerability can lead to unauthorized read/write access to files in sibling directories, potentially exposing sensitive data in shared hosting environments.
Weakness: CWE-23
Which versions are affected by CVE-2026-5422?
3 open source packages ship an affected version, including jupyter-server. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
jupyter-server PyPI | All versions | 2.18.2 |
jupyter-server PyPI | All versions | 2.18.2 |
jupyter-server PyPI | All versions | 2.18.2 |
Linux distribution packages (1)
python-jupyter-server openSUSE:Tumbleweed | All versions | 2.19.0-1.1 |
Products include Jupyter Jupyter Server.
How do I fix CVE-2026-5422?
Upgrade jupyter-server to 2.18.2 or later.
Upgrade, and resolve every user-supplied path against an allowed base folder before opening it. More about Path traversal.
Is CVE-2026-5422 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-5422 exists.
Other vulnerabilities in jupyter/jupyter
- CVE-2026-44727 Jupyter Server: Stored XSS in `NbconvertFileHandler` / `NbconvertPostHandler` via missing `sandbox` CSP
- CVE-2026-35397 jupyter-server path traversal allows access to sibling directories sharing root_dir name prefix
- CVE-2026-40110 jupyter-server CORS origin validation bypass via unanchored regex in allow_origin_pat
- CVE-2026-40934 jupyter-server authentication cookies remain valid after password reset due to static cookie secret
- CVE-2024-35178 Jupyter server on Windows discloses Windows user password hash
Sources
Also known as DEBIAN-CVE-2026-5422, GHSA-gf7q-q4j7-hp7c, PYSEC-2026-2532, UBUNTU-CVE-2026-5422, openSUSE-SU-2026:10972-1.