# CVE-2026-73626: JupyterLab allowlist/blocklist bypass in PyPIExtensionManager.install()

Source: https://junglewise.ai/threats/cve-2026-73626-jupyterlab-allowlist-blocklist-bypass-in-pypiextensionmanager  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-08-13. Updated: 2026-09-25  
License: CC BY 4.0 with a link back

CVE-2026-73626 · Severity: high · CVSS 7.5 · Published 2026-08-13

JupyterLab is an interactive development environment used by data scientists and developers for coding and data analysis. A missing code statement (an "await") in the extension installation function allows attackers to bypass security controls that restrict which third-party packages can be installed, but only if custom code directly calls the vulnerable function and the deployment has specific constraints (terminals and kernels disabled). The stock JupyterLab interface is unaffected because it performs its own security check.

Technologies: [jupyterlab (PyPI)](https://junglewise.ai/threats/technologies/pypi-jupyterlab). Vendors: [PyPI](https://junglewise.ai/threats/vendors/pypi).

## Quick answers

**Is CVE-2026-73626 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-73626 being exploited in the wild.

**How severe is CVE-2026-73626?** High severity, with a CVSS score of 7.5, published 13 August 2026.

**Which products and versions are affected?** jupyterlab (PyPI) ECOSYSTEM:introduced=4.6.0,fixed=4.6.2.

**Is there a fix for CVE-2026-73626?** Yes. jupyterlab (PyPI): upgrade to 4.6.2 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-73626 attacked?** It is attacked over the network.

**Am I affected by CVE-2026-73626?** Check whether you run jupyterlab (PyPI) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- jupyterlab (PyPI): upgrade to 4.6.2 or later

  ```sh
  pip install "jupyterlab>=4.6.2"
  ```


## Technical details

The vulnerability is an improper access control and failing-open issue (CWE-284, CWE-636) in the PyPIExtensionManager.install() method. A missing 'await' keyword caused the is_install_allowed coroutine to never execute, bypassing the allowlist/blocklist enforcement for direct method callers. The stock JupyterLab HTTP API and Extension Manager UI are unaffected because they perform a separate, correctly awaited allowlist check before invoking install(). The vulnerability only impacts deployments where custom extensions or downstream integrations call install() directly with untrusted input, an allowlist/blocklist is configured, the PyPI Extension Manager is enabled, and kernels and terminals are disabled or delegated remotely. An attacker can install unauthorized packages, bypassing security policy. Fixed in JupyterLab 4.6.2 and 4.5.10.

## Affected products

- JupyterLab JupyterLab >=4.6.0,<=4.6.1 and <=4.5.9

## Identifiers

- CVE-2026-73626
- GHSA-whvh-wf3x-g77j

## Timeline

- 2026-07-21: disclosed
- 2026-08-13: advisory
- 2026: patched: Fixed in JupyterLab 4.6.2 and 4.5.10

## References

- [https://github.com/jupyterlab/jupyterlab/security/advisories/GHSA-whvh-wf3x-g77j](https://github.com/jupyterlab/jupyterlab/security/advisories/GHSA-whvh-wf3x-g77j)
- [https://www.vulncheck.com/advisories/jupyterlab-before-authentication-bypass-via-pypiextensionmanager](https://www.vulncheck.com/advisories/jupyterlab-before-authentication-bypass-via-pypiextensionmanager)

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