Is CVE-2021-41194 actively exploited?

No active exploitation of CVE-2021-41194 has been confirmed so far. Continue monitoring, as exploit status can change.

Can CVE-2021-41194 be exploited remotely?

Yes. CVE-2021-41194 is exploitable remotely over the network (CVSS attack vector: Network).

What is the CVSS score of CVE-2021-41194?

CVE-2021-41194 has a CVSS score of 9.8 (CRITICAL).

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CRITICAL

CVE-2021-41194

CWE-284Published: October 28, 2021· Updated: Jun 17, 2026

9.8

CVSS v3.1

Official 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.

NVD Source

Technical Analysis

CVE-2021-41194 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.

The vulnerability requires no privileges and no user interaction, making it a prime target for automated exploitation campaigns and worm-like propagation.

A successful exploit results in complete confidentiality breach (data exposure), full integrity compromise (data manipulation), availability disruption (denial of service), with a CVSS base score of 9.8.