CVE-2021-41247

Name: CVE-2021-41247
Creator: NVD / NIST
Published: 2021-11-04T18:15:08.707+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

HIGHCVSS 7.5/10EPSS 0.78%

Last modified Jun 17, 2026

CVE-2021-41247 is a high-severity vulnerability rated 7.5/10 on the CVSS scale. 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. EPSS estimates a 0.78% chance of exploitation in the next 30 days.

Description

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.

Metrics

CVSS 3.1

7.5/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

EPSS Probability

0.78%

51.2th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

Vendor	Product	Versions
Jupyter	Jupyterhub	>= 1.0.0, < 1.5.0

References

https://github.com/jupyterhub/jupyterhub/commit/5ac9e7f73a6e1020ffddc40321fc53336829fe27Patch, Third Party Advisory
https://github.com/jupyterhub/jupyterhub/security/advisories/GHSA-cw7p-q79f-m2v7Third Party Advisory
https://github.com/jupyterhub/jupyterhub/commit/5ac9e7f73a6e1020ffddc40321fc53336829fe27Patch, Third Party Advisory
https://github.com/jupyterhub/jupyterhub/security/advisories/GHSA-cw7p-q79f-m2v7Third Party Advisory

Timeline

Published: Nov 4, 2021
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-41247?

How severe is CVE-2021-41247?

CVE-2021-41247 has a CVSS score of 7.5/10 (HIGH severity). The EPSS model estimates a 0.78% probability of exploitation in the next 30 days.

How do I fix CVE-2021-41247?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2021-41247?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST