---
id: GHSA-whvh-wf3x-g77j
title: >-
  JupyterLab: Allowlist/blocklist check in `PyPIExtensionManager.install()` not
  enforced for direct callers (missing `await`)
summary: >-
  JupyterLab: Allowlist/blocklist check in `PyPIExtensionManager.install()` not
  enforced for direct callers (missing `await`)
severity: low
cwe:
  - CWE-284
  - CWE-636
vendor: jupyterlab
product: jupyterlab
ecosystem: pip
affected:
  - 'jupyterlab >= 4.6.0, <= 4.6.1'
  - jupyterlab <= 4.5.9
patched:
  - jupyterlab 4.6.2
  - jupyterlab 4.5.10
published: '2026-07-22'
updated: '2026-07-22'
source: GHSA
sourceUrl: 'https://github.com/advisories/GHSA-whvh-wf3x-g77j'
references:
  - url: >-
      https://github.com/jupyterlab/jupyterlab/security/advisories/GHSA-whvh-wf3x-g77j
  - url: 'https://github.com/jupyterlab/jupyterlab/pull/19184'
  - url: 'https://github.com/jupyterlab/jupyterlab/pull/19185'
  - url: 'https://github.com/jupyterlab/jupyterlab/pull/19186'
  - url: >-
      https://github.com/jupyterlab/jupyterlab/commit/be9303f5bcd5308eaeae953c5a3c903046682c2c
  - url: >-
      https://github.com/jupyterlab/jupyterlab/commit/f1beab4a2027af4719d6edc07d52d6cf5a39a432
  - url: 'https://github.com/jupyterlab/jupyterlab/releases/tag/v4.5.10'
  - url: 'https://github.com/jupyterlab/jupyterlab/releases/tag/v4.6.2'
  - url: 'https://github.com/advisories/GHSA-whvh-wf3x-g77j'
tags:
  - ghsa
  - pip
ingestedAt: '2026-07-23T00:08:38.876Z'
---

## Overview

The extension allowlist/blocklist check inside `PyPIExtensionManager.install()` was not enforced due to a missing await. For purposes of JupyterLab this was a secondary defense-in-depth check: `install()` was intended to enforce the allowlist/blocklist itself for any future uses and users calling this method directly (in addition to the separate check handling requests arriving through the HTTP API).  The only runtime symptom was a `RuntimeWarning: coroutine 'is_install_allowed' was never awaited.`

This has security implications only for deployments that combine all of the following:
- a custom extension or downstream integration that imports `PyPIExtensionManager` and calls `install()` directly with a package name influenced by untrusted user input (the stock JupyterLab HTTP handler is not affected - it performs its own awaited allowlist check before calling `install()`);
- an allowlist/blocklist configured with the intent of restricting which packages users can install;
- the (default) PyPI Extension Manager enabled; and
- kernels and terminals disabled or delegated to remote hosts, so that the custom extension's `install()` call is the only available package-install vector (otherwise a user with kernel access can install packages directly regardless of this check)

### Impact

Low. No exposure for stock JupyterLab: the HTTP API and Extension Manager UI enforce the listing through a separate, correctly awaited check. The gap affected only custom extensions or downstream integrations that called the public `install()` method directly and relied on it to self-enforce.

### Patches

JupyterLab [`v4.6.2`](https://github.com/jupyterlab/jupyterlab/releases/tag/v4.6.2) and [`v4.5.10`](https://github.com/jupyterlab/jupyterlab/releases/tag/v4.5.10) contain the patch.

Users of applications that depend on JupyterLab, such as Notebook v7+, should update `jupyterlab` package too.

### Workarounds

No action is required for deployments that only expose extension management through the JupyterLab HTTP API / Extension Manager UI, as that path was already enforcing the listing via the handler's own check. Deployments wanting to disable programmatic extension installation entirely can switch to the read-only extension manager:

```bash
--LabApp.extension_manager=readonly
```

or the following traitlet:

```python
c.LabApp.extension_manager = 'readonly'
```

You can confirm that the read-only manager is in use from GUI:

<img width="293" height="293" alt="image" src="https://github.com/user-attachments/assets/8016c809-633e-4ed0-a5bc-6bc4793caa0f" />

## Affected packages

- `jupyterlab >= 4.6.0, <= 4.6.1`
- `jupyterlab <= 4.5.9`

## Remediation

Upgrade to a patched release:

- `jupyterlab 4.6.2`
- `jupyterlab 4.5.10`