CVE-2021-41247

What it is

JupyterHub is an open source multi-user server for Jupyter notebooks. In affected versions users who have multiple JupyterLab tabs open in the same browser session, may see incomplete logout from the single-user server, as fresh credentials (for the single-user server only, not the Hub) reinstated after logout, if another active JupyterLab session is open while the logout takes place. Upgrade to JupyterHub 1.5. For distributed deployments, it is jupyterhub in the _user_ environment that needs patching. There are no patches necessary in the Hub environment. The only workaround is to make sure that only one JupyterLab tab is open when you log out.

At a glance

Exploitability

Can be exploited over the network with a low-privilege account, but needs a user to act. Limited direct impact.

Exploit odds

0.8% chance of exploitation in the next 30 days (EPSS).

Fix

A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

1. 2021-11-04 18:15 UTC PublishedDisclosed publicly on CVE.org and NVD
2. 2026-06-17 04:08 UTC Last updatedMost recent change to the record

Why it ranks here

• Exploited in the wild: no, CISA does not list it.
• Exploit odds: 0.8% in the next 30 days (EPSS).
• Severity: 3.5 LOW (CVSS).
• Fix: a patch or advisory is linked.

Details

Published

2021-11-04 18:15 UTC

Last modified

2026-06-17 04:08 UTC

Exploit probability

0.8% · EPSS, next 30 days

Weakness

CWE-613

Record status

Modified

Affected

• Jupyter Jupyterhub < 1.5.0

Attack profile CVSS 3.1 · 3.5

Attack vector

Network

Complexity

Low

Privileges needed

Low

User interaction

Required

Scope

Unchanged

Confidentiality

Low

Integrity

None

Availability

None

Is it in your code?

Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.

Read https://cve-list.com/agent/cve/CVE-2021-41247.md and follow it. Check whether this project is affected by CVE-2021-41247. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.

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