CVE-2021-41194

Improper Access Control in jupyterhub-firstuseauthenticator

Description

FirstUseAuthenticator is a JupyterHub authenticator that helps new users set their password on their first login to JupyterHub. When JupyterHub is used with FirstUseAuthenticator, a vulnerability in versions prior to 1.0.0 allows unauthorized access to any user's account if `create_users=True` and the username is known or guessed. One may upgrade to version 1.0.0 or apply a patch manually to mitigate the vulnerability. For those who cannot upgrade, there is no complete workaround, but a partial mitigation exists. One can disable user creation with `c.FirstUseAuthenticator.create_users = False`, which will only allow login with fully normalized usernames for already existing users prior to jupyterhub-firstuserauthenticator 1.0.0. If any users have never logged in with their normalized username (i.e. lowercase), they will still be vulnerable until a patch or upgrade occurs.

Category

9.1
CVSS
Severity: Critical
CVSS 3.1 •
CVSS 2.0 •
EPSS 0.35%
Third-Party Advisory github.com Third-Party Advisory github.com Third-Party Advisory github.com
Affected: jupyterhub firstuseauthenticator
Published at:
Updated at:

References

Link Tags
https://github.com/jupyterhub/firstuseauthenticator/security/advisories/GHSA-5xvc-vgmp-jgc3 third party advisory
https://github.com/jupyterhub/firstuseauthenticator/pull/38 third party advisory patch
https://github.com/jupyterhub/firstuseauthenticator/pull/38.patch third party advisory patch

Frequently Asked Questions

What is the severity of CVE-2021-41194?
CVE-2021-41194 has been scored as a critical severity vulnerability.
How to fix CVE-2021-41194?
To fix CVE-2021-41194, make sure you are using an up-to-date version of the affected component(s) by checking the vendor release notes. As for now, there are no other specific guidelines available.
Is CVE-2021-41194 being actively exploited in the wild?
As for now, there are no information to confirm that CVE-2021-41194 is being actively exploited. According to its EPSS score, there is a ~0% probability that this vulnerability will be exploited by malicious actors in the next 30 days.
What software or system is affected by CVE-2021-41194?
CVE-2021-41194 affects jupyterhub firstuseauthenticator.
This platform uses data from the NIST NVD, MITRE CVE, MITRE CWE, First.org and CISA KEV but is not endorsed or certified by these entities. CVE is a registred trademark of the MITRE Corporation and the authoritative source of CVE content is MITRE's CVE web site. CWE is a registred trademark of the MITRE Corporation and the authoritative source of CWE content is MITRE's CWE web site.
© 2025 Under My Watch. All Rights Reserved.