JupyterLab: XSS due to lack of sanitization of the action attribute of an html <form>

CRITICAL 9.6CVE-2021-32797 · BIT-jupyterlab-2021-32797 · GHSA-4952-p58q-6crx · Published 09/08/2021 · updated 17/06/2026

In short

CVE-2021-32797 is a CRITICAL (CVSS 9.6) vulnerability affecting jupyterlab, notebook, jupyterlab (jupyter).
Chance of exploitation in the next 30 days (EPSS): 2.7%, higher than 85.7% of all vulnerabilities.
Fix: update to 2.2.10, 2.3.2, 3.0.17, 3.1.4 or later.

Package	Affected versions	Patched versions
jupyterlab PyPI	`≥ 2, < 2.2.10≥ 2.0.0a0, < 2.2.10≥ 2.3, < 2.3.2≥ 2.3.0a0, < 2.3.2≥ 3, < 3.0.17≥ 3.0.0a0, < 3.0.17≥ 3.1, < 3.1.4≥ 3.1.0a0, < 3.1.4< 1.2.21`	`2.2.102.3.23.0.173.1.41.2.21`
notebook PyPI	`≥ 6.0.0, < 6.4.1< 5.7.11`	`6.4.15.7.11`
jupyterlab jupyter	`≥ 2.0.0, < 2.2.10≥ 2.3.0, < 2.3.2≥ 3.0.0, < 3.0.17≥ 3.1.0, < 3.1.4< 1.2.21`	`2.2.102.3.23.0.173.1.41.2.21`

Description

Impact

Untrusted notebook can execute code on load. This is a remote code execution, but requires user action to open a notebook.

Patches

Patched in the following versions: 3.1.4, 3.0.17, 2.3.2, 2.2.10, 1.2.21.

References

OWASP Page on Restricting Form Submissions

For more information

If you have any questions or comments about this advisory, or vulnerabilities to report, please email our security list [email protected].

Credit: Guillaume Jeanne from Google

NVD description

JupyterLab is a user interface for Project Jupyter which will eventually replace the classic Jupyter Notebook. In affected versions untrusted notebook can execute code on load. In particular JupyterLab doesn’t sanitize the action attribute of html `<form>`. Using this it is possible to trigger the form validation outside of the form itself. This is a remote code execution, but requires user action to open a notebook.