CVE-2021-32797 is a critical-severity (CVSS 9.6) Cross-site Scripting (XSS) vulnerability in jupyterlab. 1 public exploit reference exists, so weaponization risk is real. O3 Security confirms whether CVE-2021-32797 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
JupyterLab: XSS due to lack of sanitization of the action attribute of an html <form>
Real-World Exposure
jupyterlab🐍jupyterlab🐍jupyterlab🐍jupyterlab🐍jupyterlab🐍notebook🐍notebookReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects PyPI packages — download data is not available via public APIs for these ecosystems.
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 Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐍PyPI | jupyterlab | all versions | 1.2.21 |
| 🐍PyPI | jupyterlab | ≥ 2.0.0a0&&< 2.2.10 | 2.2.10 |
| 🐍PyPI | jupyterlab | ≥ 2.3.0a0&&< 2.3.2 | 2.3.2 |
| 🐍PyPI | jupyterlab | ≥ 3.0.0a0&&< 3.0.17 | 3.0.17 |
| 🐍PyPI | jupyterlab | ≥ 3.1.0a0&&< 3.1.4 | 3.1.4 |
| 🐍PyPI | notebook | all versions | 5.7.11 |
Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for jupyterlab. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update jupyterlab to 1.2.21 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-32797 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether CVE-2021-32797 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to CVE-2021-32797. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2021-32797 in your dependencies?
O3 detects CVE-2021-32797 across PyPI dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.