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Improper Access Control in jupyterhub-firstuseauthenticator

Critical severity GitHub Reviewed Published Oct 28, 2021 in jupyterhub/firstuseauthenticator • Updated Sep 7, 2023

Package

pip jupyterhub-firstuseauthenticator (pip)

Affected versions

< 1.0.0

Patched versions

1.0.0

Description

Impact

When JupyterHub is used with FirstUseAuthenticator, the vulnerability allows unauthorized access to any user's account if create_users=True and the username is known or guessed.

Patches

Upgrade to jupyterhub-firstuseauthenticator to 1.0, or apply patch https://github.com/jupyterhub/firstuseauthenticator/pull/38.patch

Workarounds

If you cannot upgrade, there is no complete workaround, but it can be mitigated.

If you cannot upgrade yet, you 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. If any users have never logged in with their normalized username (i.e. lowercase), they will still be vulnerable until you can patch or upgrade.

References

@consideRatio consideRatio published to jupyterhub/firstuseauthenticator Oct 28, 2021
Reviewed Oct 28, 2021
Published by the National Vulnerability Database Oct 28, 2021
Published to the GitHub Advisory Database Oct 28, 2021
Last updated Sep 7, 2023

Severity

Critical

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
None

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

EPSS score

0.220%
(60th percentile)

Weaknesses

CVE ID

CVE-2021-41194

GHSA ID

GHSA-5xvc-vgmp-jgc3

Source code

Credits

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