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

> Authenticated users can bypass PyPI extension blocklists by using non-canonical package names, allowing installation of prohibited extensions.

- **Severity:** Medium 6.1 (`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`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 13 Aug 2026
- **Updated:** 17 Aug 2026
- **Also known as:** BIT-jupyterlab-2026-73416, CLEANSTART-2026-NU47623, DEBIAN-CVE-2026-73416, GHSA-89vp-jrxv-24w8, MINI-wqr5-wfg6-wf3h, PYSEC-2026-3670, UBUNTU-CVE-2026-73416

## What is CVE-2026-73416?

CVE-2026-73416 is a medium-severity vulnerability in jupyterlab, published on 13 Aug 2026. Any signed-in user can exploit it over the network, with no action from the victim.

### Official 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.

Weakness: CWE-180 (Incorrect Behavior Order: Validate Before Canonicalize), CWE-178 (Improper Handling of Case Sensitivity)

## Which versions are affected by CVE-2026-73416?

6 open source packages ship an affected version, including jupyterlab.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `jupyterlab` | Bitnami | From 4.5.0 | 4.5.10, 4.6.2 |
| `jupyterlab` | PyPI | From 4.5.0 | 4.5.10, 4.6.2 |
| `jupyterlab` | PyPI | From 4.5.0 | 4.5.10 |
| `jupyterlab` | PyPI | From 4.5.0 | 4.5.10 |
| `jupyterlab` | PyPI | From 4.6.0 | 4.6.2 |
| `jupyterlab` | PyPI | From 4.6.0 | 4.6.2 |

## How do I fix CVE-2026-73416?

Upgrade jupyterlab to a fixed version for your release line: 4.5.10 or 4.6.2.

## Is CVE-2026-73416 being exploited?

There is no known exploitation of CVE-2026-73416 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-73416 and fix it if it is affected.

What it is: CVE-2026-73416 is a medium-severity vulnerability in jupyterlab, published on 13 Aug 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-73416 in the wild and no public exploit code.

Affected packages and fixed versions:
- jupyterlab (Bitnami): affected from 4.5.0; fixed in 4.5.10, 4.6.2
- jupyterlab (PyPI): affected from 4.5.0; fixed in 4.5.10, 4.6.2
- jupyterlab (PyPI): affected from 4.5.0; fixed in 4.5.10
- jupyterlab (PyPI): affected from 4.5.0; fixed in 4.5.10
- jupyterlab (PyPI): affected from 4.6.0; fixed in 4.6.2
- jupyterlab (PyPI): affected from 4.6.0; fixed in 4.6.2

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-73416/ (Markdown: https://insights.sbomify.com/CVE-2026-73416/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-73416
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-73416
- OSV: https://osv.dev/vulnerability/CVE-2026-73416

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-73416/
Summaries are generated and may contain mistakes; the official description above is the record.