jupyterlab: PyPI extension blocklist package-name canonicalization bypass

Summary

jupyterlab is an extensible environment for interactive and reproducible computing, based on the Jupyter Notebook Architecture. From 4.5.0 until 4.5.10 and 4.6.2, in jupyterlab/extensions/manager.py and jupyterlab/extensions/pypi.py, JupyterLab's PyPI extension manager enforces blocked_extensions_uris by comparing requested install names to blocklist entries with custom normalization that is weaker than PyPI package-name canonicalization. An authenticated user can request a PyPI-equivalent spelling such as JupyterLab.Git for a blocklisted package such as jupyterlab-git, and JupyterLab accepts the install request even though pip resolves the variant to the same package. Security impact requires an allowlist or blocklist intended to restrict package installation, the PyPI Extension Manager, and kernels and terminals that are disabled or delegated to remote hosts. The bypass lets an authenticated user install a prohibited extension, defeat integrity restrictions, and affect availability without gaining new read access. This issue is fixed in versions 4.5.10 and 4.6.2.

Timeline

1. Aug 13, 2026, 10:04 PM UTCCVE published
2. Aug 17, 2026, 5:16 PM UTCCISA SSVC assessment

   Exploitation: none · Automatable: no · Technical impact: partial

3. Aug 17, 2026, 5:17 PM UTCRecord last updated

Affected versions

• jupyterlab jupyterlab

  From 4.5.0 · fixed in 4.5.10; From 4.6.0 · fixed in 4.6.2

• jupyterlabPyPI

  From 4.6.0 · fixed in 4.6.2

• jupyterlabPyPI

  From 4.5.0 · fixed in 4.5.10

• jupyterlabPyPI

  From 4.5.0 · fixed in 4.5.10; From 4.6.0 · fixed in 4.6.2

References 10