How severe is CVE-2026-73626?

No CVSS score has been assigned to CVE-2026-73626 yet. Review the advisory details and affected package list to assess your exposure.

Which packages are affected by CVE-2026-73626?

CVE-2026-73626 affects the following packages: jupyterlab (PyPI), jupyterlab (PyPI). Ecosystems affected: PyPI.

How do I fix CVE-2026-73626?

Update jupyterlab to 4.6.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-73626 is resolved across your whole dependency graph.

How do I detect CVE-2026-73626 in my PyPI dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for jupyterlab, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate CVE-2026-73626 if there is no patch (or I can't update yet)?

Put an independent control in front of the weakness: restrict the affected endpoint or interface to trusted networks, require an additional authentication factor or proxy-level check, and invalidate existing sessions and credentials in case the flaw has already been used.

Is CVE-2026-73626 actively exploited in the wild?

No public exploit code has been indexed for CVE-2026-73626 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2026-73626?

CVE-2026-73626 has an EPSS (Exploit Prediction Scoring System) score of 0.4%, placing it in the 29th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2026-73626?

CVE-2026-73626 is classified as CWE-284 (CWE-284). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was CVE-2026-73626 published, and has it been updated?

CVE-2026-73626 was published on August 13, 2026 and was last updated on October 21, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

🐍 PyPI

Not in CISA KEV

CVE-2026-73626 — jupyterlab

Fix: jupyterlab/jupyterlab#19184

CVE-2026-73626 is a CWE-284 vulnerability in jupyterlab. A fix is available for jupyterlab — see the affected versions and patch details below.

JupyterLab before 4.6.2 Authentication Bypass via PyPIExtensionManager

Also known asBIT-jupyterlab-2026-73626GHSA-whvh-wf3x-g77j

Published

Aug 13, 2026

Updated

Oct 21, 2026

Affected

2 pkgs

Patched

2 / 2

Exploits

None indexed

Exploitation data as of Oct 24, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.

Exploitation and automatability from CISA’s SSVC triage for CVE-2026-73626.

EPSS Exploitation Probability

via FIRST.org ↗

0.4%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs29th percentile — riskier than 29% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

Real-World Exposure

2 pkgs affected

🐍jupyterlab🐍jupyterlab

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects PyPI packages — download data is not available via public APIs for these ecosystems.

Description

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 and 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:

--LabApp.extension_manager=readonly

or the following traitlet:

c.LabApp.extension_manager = 'readonly'

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

Affected Packages

2 total 2 fixed

Ecosystem	Package	Vulnerable range	Fix
🐍PyPI	`jupyterlab`	≥ 4.6.0&&< 4.6.2	4.6.2`pip install --upgrade 'jupyterlab==4.6.2'`
🐍PyPI	`jupyterlab`	all versions	4.5.10`pip install --upgrade 'jupyterlab==4.5.10'`

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for jupyterlab, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update jupyterlab to 4.6.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-73626 is resolved across your whole dependency graph.
Workarounds
Put an independent control in front of the weakness: restrict the affected endpoint or interface to trusted networks, require an additional authentication factor or proxy-level check, and invalidate existing sessions and credentials in case the flaw has already been used.

Frequently Asked Questions

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 cust