CVE-2026-54527: JupyterLab Git stored XSS leading to RCE in Git History tab

CVE-2026-54527 · Severity: high · CVSS 4 · Published 2026-07-08

JupyterLab Git is an extension that allows users to manage Git repositories directly within the JupyterLab interface. A security flaw in how the extension displays renamed files allows an attacker to execute malicious code on a user's machine. By tricking a user into viewing the history of a specially crafted filename in a shared repository, an attacker can gain full control over the user's JupyterLab environment, potentially stealing sensitive data, credentials, or executing arbitrary commands.

Technologies: jupyterlab-git (PyPI). Vendors: npm, PyPI.

Quick answers

Is CVE-2026-54527 exploited in the wild?
No. Junglewise Threat Intelligence has no report of CVE-2026-54527 being exploited in the wild.
How severe is CVE-2026-54527?
High severity, with a CVSS score of 4, published 8 July 2026.
Which products and versions are affected?
@jupyterlab/git (npm) SEMVER:introduced=0.30.0-beta.3,fixed=0.54.0; jupyterlab-git (PyPI) >= 0.30.0b3, < 0.54.0a1, ECOSYSTEM:introduced=0.30.0b3,fixed=0.54.0; jupyterlab-git-core (PyPI) >= 0.30.0b3, < 0.54.0a1, ECOSYSTEM:introduced=0.30.0b3,fixed=0.54.0.
Is there a fix for CVE-2026-54527?
Yes. @jupyterlab/git (npm): upgrade to 0.54.0 or later; jupyterlab-git (PyPI): upgrade to 0.54.0 or later; jupyterlab-git-core (PyPI): upgrade to 0.54.0 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-54527 attacked?
It is attacked over the network, in a software library.
Am I affected by CVE-2026-54527?
Check whether you run @jupyterlab/git (npm), jupyterlab-git (PyPI) or jupyterlab-git-core (PyPI) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

How to fix

  • @jupyterlab/git (npm): upgrade to 0.54.0 or later
    npm install @jupyterlab/git@0.54.0
  • jupyterlab-git (PyPI): upgrade to 0.54.0 or later
    pip install "jupyterlab-git>=0.54.0"
  • jupyterlab-git-core (PyPI): upgrade to 0.54.0 or later
    pip install "jupyterlab-git-core>=0.54.0"

Technical details

A stored cross-site scripting (XSS) vulnerability exists in the `PlainTextDiff.ts` component of the jupyterlab-git extension. The `createHeader()` method improperly handles Git filenames by passing them directly to `innerHTML` without sanitization when rendering diffs for renamed files in the commit history. An attacker can exploit this by committing a file with a malicious JavaScript payload in its filename (e.g., using an `onerror` attribute in an `img` tag) and then renaming it. When a victim views the rename diff in the Git History tab, the payload executes. In the context of JupyterLab, this XSS can be escalated to Remote Code Execution (RCE) by using the injected script to steal the XSRF token and interact with the JupyterLab Terminal API. The issue is fixed in version 0.54.0 by ensuring filenames are rendered safely.

Affected products

  • jupyterlab jupyterlab-git >= 0.30.0b3, < 0.54.0
  • npm @jupyterlab/git >= 0.30.0b3, < 0.54.0

Identifiers

  • CVE-2026-54527
  • GHSA-f962-v9hr-pfg5
  • PYSEC-2026-2540
  • PYSEC-2026-2541

Timeline

  • 2026-06-17: patched: Version 0.54.0 released
  • 2026-06-18: advisory: GitHub Security Advisory published
  • 2026-07-08: disclosed: CVE-2026-54527 published to NVD

References

This page as Markdown. Free to reuse under CC BY 4.0 with a link back.