What’s Vulnerable › Vulnerabilities

CVE-2021-32797: JupyterLab: XSS due to lack of sanitization of the action attribute of an html <form>

• Severity: critical (CVSS 9.6 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 2.7% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2021-08-09 · updated 2026-06-17
• Weakness: CWE-79

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.

Affected products

• jupyterlab: before 1.2.21; from 2.0.0 before 2.2.10; from 2.3.0 before 2.3.2; from 3.0.0 before 3.0.17; from 3.1.0 before 3.1.4 — fixed in 1.2.21, 2.2.10, 2.3.2, 3.0.17, 3.1.4

How to fix

Upgrade to a fixed version: jupyterlab 1.2.21, 2.2.10, 2.3.2, 3.0.17. Check the vendor advisory for mitigations.

References

• https://github.com/jupyterlab/jupyterlab/commit/504825938c0abfa2fb8ff8d529308830a5ae42ed
• https://github.com/jupyterlab/jupyterlab/security/advisories/GHSA-4952-p58q-6crx
• https://github.com/jupyterlab/jupyterlab/commit/504825938c0abfa2fb8ff8d529308830a5ae42ed
• https://github.com/jupyterlab/jupyterlab/security/advisories/GHSA-4952-p58q-6crx

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