HTML injection in JupyterLite leading to DOM Clobbering

Impact

The vulnerability depends on user interaction by opening a malicious notebook with Markdown cells, or Markdown file using JupyterLab preview feature.

A malicious user can access any data accessible from JupyterLite and perform arbitrary actions in JupyterLite environment.

Patches

JupyterLite 0.4.1 was patched.

Workarounds

There is no workaround for the underlying DOM Clobbering susceptibility. However, select plugins can be disabled on deployments which cannot update in a timely fashion to minimise the risk. These are:

• @jupyterlab/mathjax-extension:plugin - users will loose ability to preview mathematical equations
• @jupyterlab/markdownviewer-extension:plugin - users will loose ability to open Markdown previews
• @jupyterlab/mathjax2-extension:plugin (if installed with optional jupyterlab-mathjax2 package) - an older version of the mathjax plugin for JupyterLab 4.x

To disable these extensions populate the disabledExtensions key in jupyter-config-data stanza of jupyter-lite.json as documented on https://jupyterlite.readthedocs.io/en/stable/howto/configure/config_files.html#jupyter-lite-json

{
  "jupyter-lite-schema-version": 0,
  "jupyter-config-data": {
    "appName": "My JupyterLite App",
    "disabledExtensions": [
      "@jupyterlab/markdownviewer-extension:plugin",
      "@jupyterlab/mathjax-extension:plugin",
      "@jupyterlab/mathjax2-extension:plugin"
    ]
  }
}

To confirm that the plugins were disabled manual inspection of the built page is required.

References

Upstream advisory: https://github.com/jupyterlab/jupyterlab/security/advisories/GHSA-9q39-rmj3-p4r2

Notes

This change has a potential to break rendering of some markdown. There is a setting in Sanitizer which allows to revert to the previous sanitizer settings (allowNamedProperties).