Summary
HTML injection in JupyterLite leading to DOM Clobbering
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 optionaljupyterlab-mathjax2package) - 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).
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.
Untrusted input is rendered as active markup in a victim's browser, which can run script in their session. Typical impact: session or credential theft, and actions taken as the user.
GHSA-GJ55-2XF9-67RQ has a CVSS score of 8.1 (Medium). The vector is network-reachable, no privileges required, and user interaction required. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (0.4.1); upgrading removes the vulnerable code path.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
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JupyterLite 0.4.1 was patched.
Frequently Asked Questions
- What is GHSA-GJ55-2XF9-67RQ? GHSA-GJ55-2XF9-67RQ is a medium-severity cross-site scripting (XSS) vulnerability in jupyterlite-core (pip), affecting versions < 0.4.1. It is fixed in 0.4.1. Untrusted input is rendered as active markup in a victim's browser, which can run script in their session.
- How severe is GHSA-GJ55-2XF9-67RQ? GHSA-GJ55-2XF9-67RQ has a CVSS score of 8.1 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
- Which versions of jupyterlite-core are affected by GHSA-GJ55-2XF9-67RQ? jupyterlite-core (pip) versions < 0.4.1 is affected.
- Is there a fix for GHSA-GJ55-2XF9-67RQ? Yes. GHSA-GJ55-2XF9-67RQ is fixed in 0.4.1. Upgrade to this version or later.
- Is GHSA-GJ55-2XF9-67RQ exploitable, and should I be worried? Whether GHSA-GJ55-2XF9-67RQ is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether GHSA-GJ55-2XF9-67RQ is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix GHSA-GJ55-2XF9-67RQ? Upgrade
jupyterlite-coreto 0.4.1 or later.